LWA TV on the Raspberry Pi
Contents
1. 10 0 0 1 ping statistics 5 packets transmitted 5 received 0 packet loss time 4005ms rtt min avg max mdev 1 203 1 360 1 779 0 218 ms pi Callisto Pi The pings should be successful with no packet loss If not successful then your setup is incorrect Recheck each step above If necessary you can revert to DHCP by reversing the steps or by looking at your screenshots before the changes You must reboot after making any interface changes sudo reboot Alternately instead of reboot you also can simply stop and restart the RPi network sudo etc init d networking stop sudo etc init d networking start See last page for copyright and document information File Reeve RPi LWATV doc Page 19 Appendix B Install Wireless LAN WLAN Adding a wireless LAN connection to the RPi requires only a USB wireless access device also called WLAN dongle and Wi Fi dongle and some changes to the network interface configurations Note A USB BlueTooth dongle is physically identical to the Wi Fi dongle but is not compatible with this application Most Wi Fi dongles are marked 802 11n The following steps assume the RPi is initially connected to the LAN through a a wired Ethernet cable DO NOT plugin the Wi Fi dongle until told to do so As you go through the following steps take screenshots before and after making changes this will help in case you need to reverse your changes It should be remembered that a Wi Fi don2. key mgmt WPA PSK f pairwise TKIFP t auth alg OPEN me Get Help ME WriteCut W Read File M Prey Pace WE TE Ww Justify A Where I5 M Next Fage g Note the following two lines Do not change them ctrl interface DIR var run wpa supplicant GROUP netdev update config 1 The configuration file supplied with the RPi software image includes a number of additional lines all commented out deactivated with the character Use the keyboard arrow keys to navigate the text and then make the changes necessary for your wireless network The first two parameters ssid and psk are the SSID and PASSWORD values and proto key mgmt pairwise and auth alg are the Encryption type and method mentioned in par B 2 To activate the WLAN delete the character and edit the values shown according to your network details When finished the configuration file should look something like this See last page for copyright and document information File Reeve RPi LWATV doc Page 22 z pi Callisto Pr 0 x GNU nano 2 2 6 File etc wpa supplicant wpa supplicant cont Modified ctrl interface DIR var run wpa supplicant GROUE netdev update config 1 To usa a wireless network uncomment the three lines below t Replace the fields in parentheses network ssid WLAN i psk My WLAN 1 Key Io use a wireless network uncomment the five lines below for proto key mgmt gt Protocol type can be R5N for WP2 and WPA for WPA1 Key manag
3. URUK UK UN UX UX UX UM HD UK UK UK UNUM T T M Minimum equipment list eee Power VS Raspberry Pi BorB e 4GB memory card e Power supply e Monitor or TV e HDMI cable e Ethernet cable AC Power Adapter e Optional e WiFi device e USB Keyboard mouse Figure 6 Block diagram and equipment list for the RPi when setup for LWA TV See text for description of each item Before applying power to the RPi make all connections and turn on power to the monitor or television set Image 2014 W Reeve When connected LWA TV downloads a daily average of approximately 25 kB s 91 MB h or 2 2 GB d The internet traffic is split between the real time images and archived movies The LWA station processes the data and prepares images in near real time The LWA TV GUI checks for and downloads a new image every 5 s Each image includes the total radio energy received during the 5 s interval so transient emissions lasting less than 5 s are recorded The images are about 120 kB each so the average network traffic load is about 24 kB s The archived movies are downloaded in the evening and are usually around 100 MB each Downloading uses whatever internet bandwidth is available See last page for copyright and document information File Reeve RPi LWATV doc Page 6 If your internet service has download limits and imposes penalties when exceeded it would be wise to monitor your usage Closely If you want to reduce the internet usage overnight or other t
4. is in the middle of each image Dark blue is the background and brighter areas in order of increasing radio intensity blue green yellow red are the Milky Way galaxy and spots are radio sources The locations of some of the brighter celestial radio sources are labeled The images show total intensity left and intensity of circularly polarized radio waves right Image source http www phys unm edu lwa lwatv html See last page for copyright and document information File Reeve RPi LWATV doc Page 2 Although LWA TV can be watched in near real time on any PC with internet access observers may want to setup a dedicated monitor for LWA TV and then use the PC with their own radio telescope For example one could observe Jupiter or the Sun with their own radio telescope using Radio SkyPipe RSP or Radio Sky Spectrograph RSS while watching for activity on LWA TV This allows confirmation or correlation of observations Of course the radio sources would need to be in common view of the LWA and the observer s radio telescope Another application is radio astronomy club outreach The setup could be used at meetings conventions and conferences It should be noted that LWA TV itself does not allow real time access to the actual data nor does it store any of the individual real time images 3 Raspberry Pi The Raspberry Pi abbreviated RPi throughout this article is a small computer platform designed for educational purposes by the Raspber
5. Hub RPiNet RPiIP RPiWi Fi command line SDFmt https www sdcard org downloads formatter 4 TeraTerm http ttssh2 sourceforge jp index html en WDImg http sourceforge net projects win32diskimager Acknowledgement Jayce Dowell at UNM helped me immensely with this project and hereby extend my thanks and appreciation The ratio of Jayce s knowledge of the Raspberry Pi and LWA to my knowledge is very close to infinity zero Contact Information for Preprogrammed Memory Card A preprogrammed micro SD memory card may be ordered by emailing MEMICISe Ee SIE were The micro SD card includes an SD carrier and will work in either the Raspberry Pi model B or B The cost is 15 USD including postage to any US destination and most other countries See last page for copyright and document information File Reeve RPi LWATV doc Page 14 Appendix A Change from DHCP to Static IP Address To log into the RPi console you need its IP address By default RPI obtains the address automatically from the LAN router using DHCP However the address can change whenever the RPi is removed from the network or turned off It may be preferable to operate the RPi with a static IP address an address that never changes For one thing it simplifies connection to the RPi console from an SSH terminal because the address is always known The following steps assume the RPi is connected to the LAN through a wired Ethernet interface As you go through t
6. PC and use SD Formatter to format the card In SD Formatter set the Options to Format Type Full Erase and Format Size Adjustment On 3 Download the LWA TV GUI software image for the RPi from LWASoft The file is compressed so decompress it with 7 Zip to a raw image file img This will take a few minutes 4 Write the software image to the memory card with Win32 Disk Imager using its default settings This will take a few minutes After the Write operation is finished the memory card is ready to use in the RPi Be sure RPi power is OFF and insert the card Note Some micro SD cards and card readers are incompatible so it is best to install the micro SD card in a full size SD card carrier insert the carrier into the reader and then format the card and load the software image Network Connection Error 2014 01 28 20 05 19 VIC l Figure 8 If there is a network connection problem the live globes are gray and warnings appear During normal operation the Error Downloading Image message may momentarily appear but it is nothing to worry about if it happens only occasionally Image 2014 W Reeve The RPi model B uses an ordinary push to insert pull to release slot connector whereas the model B uses a push to insert push to release slot connector When the RPi is powered ON the software will load and run automatically RPi console In order to make changes to the RPi setup described later in this section it is necessary to lo
7. address 10 0 0 11 netmask 255 255 255 0 network 10 0 0 0 broadcast 10 0 0 255 gateway 10 0 0 1 allow hotplug wlang iface wland inet dhcp wpa contf etc wpa supplicant wpa supplicant cont iface default inet dhcp Cut Text WM Cur Fos UnCut Texti To Spell i Your console should look similar to above but it will have your parameter values Now press CTRL X Exit Y Yes and then ENTER to save the changes Reboot the RPi so the changes can take effect sudo reboot A 3 Check Static IP Configuration After the RPi reboots restart the PuTTY session right click the title bar at top of PuTTY window and select Restart Session log into the RPi and enter ifconfig z pi amp cCallisto Pi inl Debian GNU Linux comes with ABSOLUTELY NO WARRANIY to the extent permitted by applicable law You have new mail Last login Sun Jan 4 21 45 58 2015 from 10 0 0 8 pi Callisto Pi sudo nano etc network interfaces pigSCallisto Pi ifconfig eth Link encap Erhernet HWaddr b8 27 eb 13 40 78 inet addr 10 0 0 11 Bcast 10 0 0 2755 M sk 255 255 255 0 UP BROADCAST RUNNING MULTICAST HMTU 1500 HMertric 1 RX packets 142 errors 0 dropped 0 overruns 0 frame IX packetrz 91 errors dropped 0 overruns 0 carrier collisions 0 txqueuelen 1000 RX bytes 12382 12 0 BiB TA bytes 13284 12 9 KiB lo Link encap Local Loopback inet addr 127 0 0 1 3HM 5k 255 0 0 0 UP LOOPBACK RUNNING MIU 65536 HMetric l1 R
8. is suspended will reduce network usage by about 91 MB It will be necessary to coordinate the start and stop times with the movie update time discussed above To use the suspension feature add the following three lines to the cron table using the cron table editor crontab e The lines shown here will start the program at 0700 and stop it at 2200 DISPLAYS US Oy python pi LWATV lwatv3 rpl py Q uL we CES OS Oka i Awat vost oL py When using this feature the RPi must be running and connected to the network Simply delete the lines if you later change your mind about using the suspension feature See last page for copyright and document information File Reeve RPi LWATV doc Page 12 Static IP and WiFi To setup a static IP address see Appendix A and to setup WiFi see Appendix B These procedures are similar to those found here RPiWi Fi and RPiIP The RPi works fine with both the Ethernet and WiFi connections enabled and it is not necessary to unplug one when using the other You will need a WiFi dongle figure 12 purchased one from Adafruit It should be remembered that a wireless dongle derives power from the RPi USB port and this power is in addition to that required by the RPi itself The dongle should be plugged into the USB port before power is applied to the RPi otherwise the RPi will reboot because of the momentary voltage drop on its power bus This is a design deficiency in the RPi x Figure 12 W
9. when it is bursting brignt that it wipes here will sometimes be point abeled ones Most c The LWA1 Site Located By the VLA Movie for February 27 Copyright c Consortium Figure 7 LWA TV screen The live image at top left shows one or two circles depending on the current LWA operating mode When LWA is setup for beam pointing only one circle may appear as shown here otherwise two appear The two circles at bottom middle are archive movies from the previous several days The movies cover a full day often with gaps and each requires about 12 minutes to run Sometimes radio frequency interference is seen along the edges of the circles The aerial image of the LWA at lower left is fixed and text on right changes depending on normal or beam pointing view of the live image Image source http fornax phys unm edu Iwa trac wiki EPO 5 Installation and Operation Notes This section provides information that will help first time users It is focused on the LWA TV application Software installation The brief instructions here assume the reader is using a Windows PC to install the LWA TV GUI software on the memory card 1 Install 7 Zip 7 Zip SD Formatter SDFmt and Win32 Disk Imager See last page for copyright and document information File Reeve RPi LWATV doc Page 7 WDImg on the Windows PC When running the latter two programs run them as Administrator 2 Put the memory card in a card reader see Note below connected to the
10. with the RPi B All the information available from the Raspberry Pi Foundation for the model B insists that it is software compatible with the model B but found there were problems that affected the LWA TV GUI These were resolved in September 2014 and the software image now available from UNM works fine on both the B and B Table 1 Comparison of Raspberry Pi Model B and B Hardware Description RAM Memory card Processor system Video 1 connector Video 2 connector Audio connector USB connector Power connector GPIO connector Network connector Power Dimensions Mounting Cost RPi B 512 MB SD BCM2835 SOC Standard HDMI RCA Composite 3 5mm 2 micro USB 26 pin 10 100 Ethernet 5V 5W 85 x 56x 21 mm 2 holes 35 USD RPi B 512 MB micro SD BCM2835 SOC Standard HDMI 3 5 mm audio Composite see Video 2 4 micro USB 40 pin 10 100 Ethernet 5 V 3W 85x 56x21 mm 4 holes 35 USD Hardware The Raspberry Pi can be purchased from any number of suppliers worldwide It is necessary to add a Secure Digital SD to the model B or micro SD memory card to the model B for the LWA TV software image Sometimes the vendor supplies a card with the RPi purchase A card with 8 GB minimum capacity is recommended but 4 GB is sufficient Also an HDMI monitor is needed A VGA monitor may be used if an HDMI to VGA converter figure 4 is connected between RPi and the monitor A keyboard with or without a mouse mig
11. 255 255 0 UP BROADCAST RUNNING MULTICAST HMTU 1500 HMertric 1 RX packets 199383 errors 0 dropped 0 overruns 0 frame TR paeck ets 193416 errore 0 dropped 0 averruns carrier collisions 0 txqueuelen i000 RX bytes 34234687 32 6 MiB TX bytes 43215623 41 2 MiB lo Link encap Local Loopback inet addr 127 0 0 1 Maske 255 0 0 0 UP LOOPBACK RUNNING MIU 65536 Me tric l1 RA packets 0 errors 0 dropped 0 overruns 0 frame 0 TX packets 0 errors 0 dropped 0 overruns 0 carrier collisions 0 rtxqueuelen RA bytes 0 0 B IX Bytes 0 0 0 B pi Callisto Pi Note the information to the right of ethO eth0 Link encap Ethernet HWaddr b8 27 eb 13 40 76 inet addr 10 0 0 11 Bcast 10 0 0 255 Mask 255 255 255 0 In the above example inet addr 10 0 0 11 current IP address example Beast 10 0 0 255 broadcast IP range example Mask 255 255 255 0 subnet mask example Your console screen most likely will show different values Copy the following details from your console inet addr your current IP address Beast your broadcast IP range Mask your subnet mask Now enter the following at the prompt netstat nr g pi Callisto Pr iface default inet dhcp pigCallisto Pi ifconfig eth Link encap Ethernet HWaddr b8 27 eb 13 40 78 inet addr 10 0 0 11 Bcast 10 0 0 255 HM ask 755 255 255 0 UP BROADCAST RUNNING MULTICAST HMTU 1500 HMetric 1 RX DpDacketz 1998383 errors 0 dropped 0 overruns 0 frame 0 TX pack
12. ALTEK gt Mode Hanaged Frequency 2 437 GHz Access Point 00 90 430C 91 00 01 Bit Rate 54 Mb s Sensitivity 0 0 Retry off RTS thr off Fragment thr off Power Management off Link Quality 100 100 Signal level 100 100 Noise level 0 100 R invalid nwid REx invalid crypt 0 Ex invalid fragi Tx excessive retries Invalid misc 0 Missed beacon ln no wireless extensions eth no wireless extensions pigCallisto Pi netstat nri Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 0 0 0 0 10 0 0 1 0 0 0 0 UG 0 0 0 e tho 10 0 0 0 0 0 0 0 255 255 255 0 U 0 0 0 erh 10 0 0 0 0 0 0 0 2050 24020 2905 0 U 0 0 0 wlanO You have new mail in var mail pi pi Callisto Pi J At the bottom of the window is a routing table In this example the wired Ethernet cable was left connected so it shows both the wired Ethernet ethO and wireless LAN connection wlanO The following commands also can be used to check the quality of the wireless connection sudo iwlist wlan scan See last page for copyright and document information File Reeve RPi LWATV doc Page 25 f pi Callisto Pr pi Calliste Pi 5 sudo iwlist wlan scan wlan Scan completed Cell 01 Cell 02 Address 00 90 43C 31 00 01 ESSID ReeveGcCI Pr tocol TEEE 802 31bq Mode Master Frequency 2 437 GHz Channel 6 Encryption key on Bit Rates 54 Mb s Extra wpa ie dd180050f 20101000050f 20201000050f 202010000250
13. ATV doc Page 1 the software for the LWA TV graphical user interface GUI is prepackaged by UNM and available for free When started working on this project August 2014 UNM s software worked only with the Raspberry model B contacted Jayce Dowell at UNM and he updated the software to run on both the model B and B the B is the latest Raspberry Pi hardware version Although the LWA TV software is plug and play there is room for some customization which describe in section 5 started writing this article to answer most of the questions that might arise while setting up the LWA TV application and ended up writing a reference manual The first half provides general descriptive information and the second half contains setup details 2 Long Wavelength Array The LWA is used to study celestial objects or areas of the radio sky in the Meses mirer ver links fa eme d frequency range 10 to 90 MHz Its primary purpose is scientific but and references in brackets education and public outreach are important parts of its government funded APOYO EE Wyse cone mission One of the features of the LWA website is LWA TV a near real time visual representation of the data produced by the array figure 2 37 80 MHz M Figure 2 Image from LWA TV as seen on the internet The two circles represent the sky seen by the LWA at radio frequencies in this case 37 80 MHz The horizon is along the circle edges and the zenith straight up
14. EX packets 0 errors 0 dropped 0 overruns 0 frame TX packets 0 errors 0 dropped 0 overruns 0 carrier collisions 0 rtxqueuelen RA Bytes 0 0 0 B IX Bytes 0 0 0 H pi Callisto Pi See last page for copyright and document information File Reeve RPi LWATV doc Page 18 Double check your work by pinging the gateway the c 5 command line switch indicates to ping 5 times Note Without the c 5 switch the address will be pinged continuously To stop continuous ping press CTRL C Also be sure to use the IP address of your gateway router and not the one shown here Ding 10 0201 E 5 z pi Callisto Pr E inl x IX packets 94 errors 0 dropped 0 overruns 0 carrier collisions txqueuelen 1000 RX bytes 12854 12 5 KiB TX bytes 14027 13 6 KiB lo Link encap Local Loopback inet addr 127 0 0 1 3HM 5k 255 0 0 0 UP LOOPBACK RUNNING MTU 65536 Metric i RX packets 0 errors 0 dropped 0 overruns 0 frame 0 TX packets 0 errors 0 dropped 0 overruns 0 carrier collisions txqueuelen RX bytes 0 0 0 B IX bytes 0 0 0 B piSCaillisto Pi ping 10 0 0 1 c 5 PING 10 0 0 1 10 0 0 1 56 84 bytes of data 64 bytes from 10 0 0 1 icmp reg 1 ttl1 64 time 1 35 ms 64 bytes from 10 0 0 1 icmp redqg 2 ttl1 64 time 1 20 ms 64 bytes from 10 0 0 1 icmp redqg 3 tt1 64 time 1 22 ms 64 bytes from 10 0 0 1 icmp req 4 tt1 64 time 1 24 ms 64 bytes from 10 0 0 1 icmp reg 5 ttl1 64 time 1 77 ms
15. Hz but found no other indications did not make any measurements with the aluminum enclosure on the model B It should be noted that conducted interference in connecting cables often is radiated because the cables act like antennas so each installation will have different RFI characteristics and it may be necessary to install ferrite beads on all connecting cables Video monitor The RPi uses a standard HDMi connector for video It may be used with a monitor or TV with an HDMI input It also may be used with a VGA monitor by using an HDMI to VGA converter or with a DVI monitor or TV with an HDMI to DVI converter experimented with the HDMI and VGA interfaces on monitors and televisions but did not attempt to use DVI For portable use say at a convention a small screen monitor would be handy Many compatible types are available for example search monitor at Adafruit to see a variety of 5 6 7 and 10 1 in monitors with HDMI inputs have not tried any monitors TVs except those discussed below initially connected the RPi to the HDMI port on a Hannspree HF 199 monitor The HF 199 has HDMI and VGA input connectors and its maximum resolution is WXGA 1440x900 pixels 16 10 aspect ratio found that the displayed image was slightly elongated horizontally when using the LWA TV GUI default settings To change the video settings it is necessary to edit the config txt file in the boot folder of the RPi It is best to do a little researc
16. LWA TV on the Raspberry Pi Whitham D Reeve 1 Introduction This article describes how to use the tiny and inexpensive Raspberry Pi computer with the Long Wavelength Array in New Mexico to observe celestial radio sources in near real time LWAT figure 1 The application was developed by the University of New Mexico UNM as Abbreviations DHCP Dynamic Host Configuration Protocol DVI Digital Visual Interface GUI Graphical User Interface HDMI High Definition Media Interface IP Internet Protocol LAN Local Area Network LWA Long Wavelength Array RPi Raspberry Pi UNM University of New Mexico VGA Video Graphics Array part of LWA Education and Public Outreach It is a good way to become familiar with the LWA LWA TV and the Raspberry Pi all at the same time The LWA TV program does not allow user control only observation and it runs out of the box with no user programming whatsoever Figure 1 The Long Wavelength Array in New Mexico consists of a forest of 257 crossed dipole tied fork antennas Beams are formed through signal processing to observe specific celestial radio sources or areas of the sky Image 2014 W Reeve One of the advantages of the approach described here is that no hardware construction or software programming is required off the shelf hardware and software is all that is needed Another advantage is that See last page for copyright and document information File Reeve_RPi LW
17. e See last page for copyright and document information File Reeve RPi LWATV doc Page 8 cd LWATV svn update updateMovies py v sudo rpi update sudo reboot It is a good idea to routinely update the Raspbian software distribution as well Send the following commands with an SSH terminal to update the non LWA TV software these updates and upgrades can require tens of minutes if new distributions have become available after the last update sudo apt get update sudo apt get upgrade lt 2 PuTTY Configuration n Category El Session Basic options for your PuT TY session d UN Specify the destination you want ta connect to Er lemina poe Keyboard Host Name or IP address Port ks Bell 10 0021 22 i Features Connection type I Window C Raw C Telnet Rlogin SSH f Serial b Appearance Behaviour Load save or delete a stored session Translation Saved Sessions Selection o Colours Default Settings El Connection Load Save Dee Delete lb Close window on exit C Aways C Never Only on clean exit re piglwatvgut login as pi pi8i10 0 0 21 s password Linux lwatvgui 3 12 26 707 PREEMPT Sat Aug 30 17 39 19 BST 2 The programs included with the Debian GNU Linux system are fre the exact distribution terms for each program are described in individual files in usr share doc copyright Debian GNU L
18. e internet to correctly set time and date To confirm the date time and time zone enter the following at the RPi prompt on the SSH terminal date To change the time zone enter the following The displayed instructions will lead you through the reconfiguration sudo dpkg reconfigure tzdata To confirm the scheduled download time for the daily LWA TV movie archive update enter the following to see what is in the cron table cron is a utility that runs automatically in the background at specified times Girontab i You should see a number of comments with the last two lines as follows m h dom mon dow command 30 18 python pi LWATV updateMovies py The last line is the scheduled event with a time of 1830 in the system time zone It is shown in crontab with minutes before the hour To change the scheduled time enter the following to edit the cron table This will invoke the default editor and allow you to change the time in the table Do not change anything on the last line except the minutes and hour crontab e The crontab function also can be used to temporarily stop and then restart the LWA TV application software at regular intervals to reduce network usage For example you could use a stop process at a specified time say 2200 in the evening and then a start process the next morning at 0700 The stop and start times can be set as required and are easy to change depending on observation activities Each hour the software
19. ed to directly access the RPi or cannot access it indirectly using SSH as described above Small wired or wireless keyboards with or without a mouse figure 10 are available from Adafruit See last page for copyright and document information File Reeve_RPi LWATV doc Page 9 Figure 10 Wireless keyboard and mouse uses a Bluetooth connection The keyboard is about 285 mm long A Bluetooth dongle is included and requires one USB port as seen on the left of the RPi model B in the image Image 2014 W Reeve Heat The RPi processor normally runs warm but not hot While using LWA TV measured about 30 C using an infrared non contact thermometer pointed at the processor chip Enclosure Many different types of enclosures are available for the model B and B RPi but the enclosures for one model do not fit the other Most enclosures are plastic and provide no shielding whatsoever This might be of concern where the RPi is used near a radio telescope antenna or receiver An expensive aluminum enclosure is available for the model B and it should provide better shielding Radio frequency interference took some measurements with a spectrum analyzer and a shielded magnetic loop probe and electric field probe and found several spectral spikes in the high MF and low HF ranges about 1 5 to 8 MHz or so These were apparent only when the probes were held against the clear plastic enclosure of the model B checked up to several hundred M
20. ement can be WPA P5EK or WPA EAP Pre S5hared or Enterprise Pairwise can be CCMP or TEIE for WPA2 or WBA1 Authorization should be OPEN for both WPA1 WPA2 less common are SHARED and L Be sure to uncomment the closing brace j se cbe che cHe che che ANE protog WBA key mgmt WPA PSEK pairwise TEIP auth alg OPEN Mi Prey Pace WE my ext Pace p me Get Help ME WriteCut MS Read File a Exit AY Justify MU Where Is When done editing the file press CTRL X Exit Y Yes and ENTER to save and exit the configuration file If you have more than one Wi Fi network at your station you can add the details for each network in the wpa_supplicant conf file The RPi will then connect to the one with the best signal For a setup with multiple networks the text lines network additional network details will need to be determined and specified for each network Now shut down the RPi sudo halt All LED indicators on the RPi board except the red power LED will extinguish when the shutdown is complete When the shutdown is complete remove power B 4 Install the WLAN Dongle With power disconnected from the RPi unplug the Ethernet cable and plug the WLAN dongle into any USB port on the RPi Connect power to RPi As it boots the power LED red will be steady and the Activity LED should flash After a moment the RPi should automatically connect to your wireless access point The RPi is setup to use DHCP and will request an IP addr
21. er to the RPi 1 HDMI connection to your monitor or television set be sure it is turned on 2 Ethernet connection to your internet router and 3 micro USB connection to an ac power adapter When power is applied the RPi system automatically starts and the display will show lines of text that scroll by rather quickly Upon completion of the boot up process the display will momentarily blank and then the LWA TV GUI will appear The LWA TV GUI shows the real time images plus archived movies figure 7 If the program is running but does not have a proper network connection you will see Error Downloading Image and Network Connection Error on the display figure 8 An archived movie may be running but the live portion of the display will be gray The LWA TV GUI connects within a second or two after the network connection is established did not have to make any changes in my internet router for LWA TV but if you have network connection problems your router and its firewall are the first place to start troubleshooting after checking that the cable is plugged in If everything seems to be working okay it is a good idea to update both the software and the archived movies upon first use Log into the RPi console as discussed in the RPi console part of section 5 and execute the commands given in the Update part Memory Monitor Network Raspberry Pi or IV y Model B or B te te Wavelength Array Station 1
22. ess from the router Most WLAN dongles have a status LED which should flash when initialized The LED will flash at about 1 Hz rate with occasional shorter irregular flashes indicating activity If the status LED does not light at all or continues to flash at only 1 Hz rate for more than a minute with no occasional flashes there may be a problem in your setup You will not be able to log into the RPi until you determine the wireless IP address and then setup the SSH client PuTTY to use that address Check your router or use a network scanning program for example SoftPerfect See last page for copyright and document information File Reeve RPi LWATV doc Page 23 Network Scanner NetScan to find the hostname same hostname as the wired network connection but this time it most likely will have a different IP address If the RPi fails to appear on the network you can plug the Ethernet cable back in log into the wired Ethernet interface and double check the above steps You most likely made a typing error After finding and fixing the error you can either restart the network interface or reboot the RPi To restart the network interface without rebooting the RPi at the prompt enter sudo etc init d networking restart Disconnect the wired Ethernet cable and log into the wireless interface using the wireless IP address Remember do not insert or remove the WLAN dongle with power applied to the RPi but it is okay to remove and install t
23. ets 193416 errors 0 dropped 0 overruns 0 carrier collisions 0 txqueuelen 1000 RX bytes 34234687 32 6 MiB TX bytes 43215623 41 2 MiB lo Link encap Local Loopback inet addr 127 0 0 1 Mask 2755 0 0 90 UP LOOPBACK RUNNING MTU 65536 Metric i RA packers 0 errors dropped 0 averruns frame IX packets 0 errors 0 dropped 0 overruns 0 carrier collisions 0 txqueuelen RX bytes 0 0 0 B IX bytes 0 0 0 B pi Callisto Pi netstat nr Kernel IP routing table Destination Gateway Genmask Flags M55 Window irtt Iface 0 0 0 0 10 0 0 1 0 0 0 0 UG 0 0 0 tho 10 0 0 0 0 0 0 0 255 255 255 090 U 0 0 0 tho pi Callisto Pi JJ See last page for copyright and document information File Reeve_RPi LWATV doc Page 16 Note the information shown in the Destination and Gateway columns Destination 10 0 0 0 network destination Gateway 10 0 0 1 gateway address Your console screen most likely will show different values Copy the following details from your console Destination your network destination Gateway your gateway address A 2 Edit the network configuration Use the built in editor nano to edit the network interface configuration file sudo nano etc network interfaces g pi Calliste PE GNU nano 2 2 6 File etc network interfaces auto lo iface lo inert loopback iface e amp eth inet dhcp Uncomment the following 5 lines and replace the network addresses address 10 0 0 11 net
24. f 2020000 IE WPA Version 1 Group Cipher TEIP Pairwise Ciphers 1 TEIP Authentication Suites 1 PSE Duality 100 100 Signal level 100 100 Address 00 15 B5 4F 38 B81 ESSID GCI 2 Pr tocol IEEE 802 11bq Mode Master Frequency 2 412 GHz Channel 1 Encryption Eey on Bit Rates 54 Mb s Extra wpa ie dd180050T20101000050f20201000050fT20201000050f2020000 IE WPA Version 1 Group Cipher TEIP Pairwise Ciphers 1 IKIP Authentication Suites 1 PSE Quality 0 100 Signal level 60 100 pig amp Callisto Pi See last page for copyright and document information File Reeve RPi LWATV doc Page 26 Document information Author Whitham D Reeve Copyright 2014 W Reeve Revision 0 0 Original draft started 29 Aug 2014 0 1 Numerous additions based on model B 9 Sep 2014 0 2 Draft completed 16 Sep 2014 0 3 Added suspension feature 17 Sep 2014 0 4 Added equipment list 18 Sep 2014 0 5 Added warnings 22 Sep 2014 0 6 2 Draft completed 30 Sep 2014 0 7 Added Administrator 4 Oct 2014 1 0 Corrected a couple spelling errors and distributed 27 Nov 2014 1 1 Minor clarification beam pointing view 06 Jan 2015 1 2 Added Appx A and B 05 Feb 2015 See last page for copyright and document information File Reeve RPi LWATV doc Page 27
25. g into the RPi console This may be done from a Windows PC that is on the same network as the RPi or through a wireless or wired keyboard The RPi uses secure shell SSH for console communications so it is necessary to install an SSH client application such as PuTTY or TeraTerm on your PC if using the network connection To use SSH first determine the IP address assigned to the RPi by your internet router Procedures vary widely and it is best to read your router user manual or search for online help The RPi host name is Iwatvgui without quotes and will be identified as such in your router s local network status screen An alternate and perhaps quicker method is to download and install on a Windows PC a network scan program as described at RPiNet For PuTTY place the RPi IP address into the Host Name or IP address field and click Open figure 9 After authentication you will see the RPi login prompt The default username is pi without quotes After you enter the username RPi will ask for the password For obvious reasons will not publish the password here but it can be obtained by emailing the address given at the very bottom of LWA EPO Updates To update the LWA TV software and archived movie cache send the following commands one at a time using the SSH terminal described above Wait for each process to complete before entering the next command It is necessary to send these commands only upon first use of the LWA TV GUI imag
26. g more than a text editor is needed to write or modify an application Notepad is perfect for this purpose and is free Notepad but Windows Notepad will also work The advantage of Notepad is that it automatically formats and indents the code to make it easier to read and work with The main piece of software in the LWA RV GUI is waTV3rpi py about 16 5 kB of text Examining the code shows that it includes four command line switches or options which may be used to customize the GUI The program operates normally with its default settings and there is no compelling reason to change them except for experimental purposes Using these options requires knowledge of the operating system and will not discuss them further 4 LWA TV on Raspberry Pi The setup for LWA TV is very simple figure 6 By default the LWA TV GUI uses the wired network interface Ethernet built into the RPi and acquires a network IP address automatically using dynamic host configuration protocol DHCP You can change this to a static IP address and add a WiFi interface However to eliminate many See last page for copyright and document information File Reeve RPi LWATV doc Page 5 potential problems recommend first running the LWA TV GUI in its default configuration to become familiar with it before making any changes See section 5 for some changes that you might find useful With the programmed memory card installed make all connections before applying pow
27. gle derives power from the RPi USB port and this power is in addition to that required by the RPi itself The dongle should be plugged into the USB port BEFORE power is applied to the RPi otherwise the RPi will reboot because of the momentary voltage drop on its power bus This is a design deficiency in the RPi and can result in program corruption B 1 WLAN Dongle WLAN dongles are inexpensive and easy to obtain for example the Edimax EW 7811Un Nano 150Mbps 802 11n Wi Fi USB Adapter costs 7 USD These devices have a very small antenna so their range is limited but 3 m between the dongle and a wireless router or wireless access point should be achievable in most situations Caution Some WLAN dongles use power management by default and they will go into sleep mode after a period of inactivity Sleep mode is manifested as a dead Wi Fi connection from which the device will not recover without rebooting the RPi This is a well known problem when these devices are used in the RPi and the solution depends on the chipset used in the dongle itself The software image includes a configuration file that solves this problem for the RealTek 8192cu RTL8188CUS chipset used in many Wi Fi dongles If your Wi Fi dongle has that chipset you should not have any problems If your WLAN device does not operate reliably then you will have to revert to a wired network connection B 2 Wi Fi Setup Details Check the configuration of the Wi Fi access point t
28. h on the internet before making any changes Use nano to edit the file nano is a simple text editor built into the software image See last page for copyright and document information File Reeve RPi LWATV doc Page 10 sudo nano boot config txt After making the desired changes and saving the file reboot the RPi sudo reboot tried changing the RPi video settings to different screen resolutions and eventually found that only one HDMI mode provided a better display and that was at the monitor s maximum resolution 1440x900 hdmi group 2 hdmi_mode 47 However at this high resolution the real time display and archive movies sometimes would momentarily stall or skip then tried an HDMI to VGA converter on the monitor s VGA input and could not obtain a good display With many settings had no display at all soent about one full day trying different port settings on the monitor and RPi finally gave up and settled on using only the monitor s HDMI port This monitor works very well at 1440x900 pixel resolution with the VGA interface on the lab PC also tried our Philips 47 in LCD television set This TV has three HDMI ports and supports several resolutions 480p 720p 1080p and 1080i found could obtain a nice picture using RPi settings for 720p hdmi_group 1 hdmi mode z4 and overscan overscan right 40 overscan_left 40 overscan_top 16 overscan bottom 16 figure 11 Although this TV supports 1080p and 1080i could no
29. he following steps take screenshots before and after making changes this will help in case you need to reverse your changes A 1 Check the existing setup Log into the RPi using PuTTY and enter the following at the prompt The default user and password is pi and Callisto X without quotes cat etc network interfaces 5 pigCallisto Pi iul xl pi Callisto Pi pi Callisto Pi pig amp Callisto Pi pi Callisto Pi pi Callisto Pi pi Callisto Pi pi amp Callisto Pi pig amp Callisto Pi pi Callisto Pi pig amp Callisto Pi pi Callisto Pi pif Callisto Pi pig amp Callistao Pi pi amp Callisto Pi auto lo beh babe bb bb ebbe Oy cia dr dr dk 4k d dk dkr dn d d d du cat etc network interfaces iface lo inet loopback iface eth inet dhcp allow haoatplug wland iface wland inet manual wpa r aam etc wpa supplicant wpa supplicant cont iface default inet dhcp pi Callisto Pi Note the line that indicates the interface named ethO uses DHCP iface ethO0 inet dhcp Enter the following at the prompt lfconfig See last page for copyright and document information File Reeve RPi LWATV doc Page 15 g pi Callisto PE iface eth inet dhcp allow hotplug wlang iface wland inet manual wpa raam etc wpa supplicant wpa supplicant conf iface default inet dhcp pi Callisto Pi ifconfig eth Link encap Erthernet HWaddr b8 27 eb 13 40 78 inet addr 10 0 0 11 Bcast 10 0 0 255 MHM sk 255
30. he wired LAN connection with power on It is recommended that either wireless LAN or wired LAN be used but not both at the same time If wired LAN is to be used remove the WLAN dongle with RPi power off If wireless LAN is to be used remove the wired LAN connection After logging into RPi you can check the wireless connection quality At the RPi prompt enter iwconfig P pi Callisto Pr ajoj x pigCallisto Pi pi Callisto Pi pig amp Callisto Pi pifCallisto Pi pi Callisto Pi pi Callisto Pi pi amp Callisto Pi pig amp Callistoco Pi pi Callisto Pi pigSCallisto Pi iwconfig wlan IEEE B802 11bg ESSID ReeveGCI Nickname WIFIGREALTEK Mode Managed Frequency 2 437 GHz Access Point 00 90 4C 91 00 01 Bit Rate 54 Mb s Sensitivity 0 0 Retcry ort RIS thr off Fragment thr off Power Management ofitf Link Quality 100 100 Signal level 100 100 Noise level 0 100 Bx invalid nwid 0 Rx invalid crypt 0 Ex invalid frag 0 Tx excessive retries 0 Invalid misc 0 Missed beacon br Xr d de dk de de de d den lo no wireless extensions eth no wireless extensions pi Callisto Pi J To the right of the wlanO interface the details include the SSID frequency bit rate link quality signal level and noise level plus other information about the wireless connection To see packet information and IP addresses for all connected interfaces enter in the following example both the wired and wireless con
31. ht be handy but is not necessary No changes are required to the RPi platform but it should be installed in an enclosure A Secure SHell SSH terminal generally is used to communicate and manage RPi from another computer on the same network This is described in more detail in section 5 Figure 4 HDMI to VGA converter allows the RPi to be used with most computer monitors The ones shown here cost about 10 USD The RPi requires a full size HDMI connector seen on the left converter An adapter will be needed If the converter has a mini HDMI connector as seen on the right converter Image O 2014 W Reeve The power requirements of the RPi are modest about 5 W for the model B and 3 W for the B assuming no current is being drawn from the USB ports Because these powers are more than supplied by a standard USB port on a PC it is necessary to use an external power supply or power adapter If no USB peripherals are used the RPi can be powered by a well regulated low ripple electrically quiet power source rated 2 1 0 A at 5 0 Vdc See last page for copyright and document information File Reeve RPi LWATV doc Page 4 gt 5 W If the RPi USB ports are to supply power to peripherals then a 10 W or higher power source should be used Using a poor quality power supply will lead to unreliable operation so be sure it meets these requirements One of the most common problems users have with the RPi is inadequate power supply current To minimi
32. iFi dongle provides wireless access and uses one USB port found the distance from the RPI to the wireless access point to be surprisingly good 3 m in spite of its very small ay antenna Image source unknown The following commands can be used to check the quality of the wireless connection after it has been setup sudo iwlist wlanO0 scan Or sudo iwconfig Downtime Sometimes the LWA TV does not seem to be working or the display does not properly render the archive movies or live presentation You may see Error Downloading Image and Network Connection Error on the display for brief periods This does not appear to be a fault with the RPi but possibly with the network connection or the UNM server and related maintenance activities It also may occur during the transition from normal view to beam pointing view at LWA1 The outages do not last long maybe tens of minutes at most and always self corrected in other words just let the RPi run and never rebooted it If you suspect your WiFi connection confirm connectivity as described in the previous item Backup You will want to backup your memory card after any major changes You will need this backup if you corrupt the program so badly that it will not boot There are several ways to run a backup If you are a Windows user you can use Win32Disklmager the same program used to Write the image to the memory card in the first place However to backup you will Read the image Thi
33. imes you can simply unplug the Ethernet cable rather than shutting down the RPi If you use a wireless network connection you will need to use a software method to stop network usage The LWA TV application updates the movie archive cache at 1830 in the time zone used by the RPi By default the LWA TV software uses mountain daylight time MDT but both the time zone and movie cache update time can be changed See Date time and time zone in section 5 for these and a method to suspend the software at night or outside normal observation times to reduce network usage o WWATV GUI 0 Mx Latest LWATV Image 2014 03 07 00 15 40 UTC 37 30 MHz e a chow the Gly a the Wer WA Ghanisy l ai vag IV hey upd te eve fe sae or lc a id if the mane erit l Cye A cy updating right now it s probably because we are running Which we do for many hours ows the full sky down to the horizon at the amp The left shows the total intensity and the right shows the intensity of circulany polarized radi aves At the yer left you can see he average time of the data that went Into the Image gwen in UTC which is wich Mean Time There is no MB we are imaging sky in real ycle At the upper right is the nage in the center is a 100 KHz Tum rom singe antenna ana polarization the images are produced from the middle 75 we ye labeled the brightest objects in the sky ova remnant upergiant elliptical galaxy also known as MB7 Crab a supernova remnant
34. inux comes with ABSOLUTELY NO WARRANTY to the ext permitted by applicable law Last login Mon Sep 38 10 35 22 2014 from 10 0 0 76 pig amp lwatvgui xi The server s host key is not cached in the registry You have no guarantee that the server is the computer you e think it is The server s rsa key fingerprint is sshtsa 2048 99 43 a2 01 37 ba cZ 2b pbe fa fico 56 If you trust this host hit Yes to add the key to PuTTY s cache and carry on connecting If you want to carry on connecting just once without adding the key to the cache hit No If you do not trust this host hit Cancel to abandon the connection Figure 9 Upper left Screenshot of PuTTY configuration window with the IP address for one of my setups Upper right Upon first connection PuTTY asks for authentication Lower left When PuTTY is connected the window changes to a simple command line interface After login you can make changes to the RPi Images 2014 W Reeve Documentation Online documentation for the Raspberry Pi including troubleshooting information is available at RPiDoc and RPiHub There also are numerous forums that have information related to RPi The only documentation that exists for the LWA TV application is this article and information at LWA EPO Keyboard mouse The LWA TV GUI has built in drivers for a USB keyboard and mouse but they are not required for normal operation However a keyboard is nice to have if you ne
35. mask 2755 255 255 0 network 10 0 0 0 broadcast 10 0 0 255 gateway 10 0 0 1 zs che che che che che ANE allow hotplug wlang iface wlan inet dhcp wpa cont etc wpa supplicant wpa supplicant cont iface default inet dhcp me Get Help ME WriteCut Be Read File fy Prey Page Wa Cut Text Jw Cur Pos Ei Pit mm Justify AU Where Is MEM Next Page WU UnCut Texti To Spell i Using the keyboard cursors move to the end of the line that reads iface ethO0 inet dhcp Replace dhcp with static as in iface ethO0 inet static Directly below the iface line uncomment delete the character the following lines and replace the address parameters with those you obtained previously Do not enter the text in parentheses below dt dt dt address 10 0 0 11 use the inet address netmask 255 255 255 0 use the subnet mask network 10 0 0 0 use the network destination broadcast 10 0 0 255 use the broadcast IP range gateway 10 0 0 1 use the gateway address The address field is the static IP address to be assigned to the RPi It does not necessarily have to be the address originally assigned by the LAN router but it must be within the router s network range See last page for copyright and document information File Reeve RPi LWATV doc Page 17 f pi Callisto Pr CNU nang auto lo iface lo inet loopback iface etrh inet static E Uncomment the following 5 lines and replace the network addresses
36. nections are active ifconfig See last page for copyright and document information File Reeve RPi LWATV doc Page 24 Pare lol pi Callisto Pi ifconfig echo Link encap Erhernet HNaddr b83 27 eb 13 430 76 inet addr 10 0 0 11 Bcast 10 0 0 2755 M sk 255 255 255 0 UP BROADCAST RUNNING MULTICAST MIU 1500 HMetric 1 RX packetrs 2650 errors 0 dropped 3 overruns 0 frame IX packets 1176 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 1000 RX bytes 370496 361 8 FiB TA bytes 698940 662 5 KiB lo Link encap Local Loopback inet addr 127 0 0 1 Maske 255 0 0 0 UP LOOPBACK RUNNING MTU 65536 Metric i RA packets 26 errors 0 dropped 0 overruns 0 frame 0 TX packets 26 errors 0 dropped 0 overruns 0 carrier collisions 0 txqueuelen RA bytes 2704 2 6 KiB TX bytes 2704 2 6 KiB wlan Link encap Erhernet HWaddr 00 e3 a7 283 ba 933 inet addr 10 0 0 37 Bcast 10 0 0 255 H 3k 2755 255 255 0 UP BROADCAST RUNNING MULTICAST HTU 1500 Me tric i RA packets 2386 errors 0 dropped 53 overruns 0 frame 0 TX paeckets 21 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 1000 RA bytes 804178 785 3 KiB TX bytes 25977 2 9 KiB pi Callisto Pi You also can obtain information about your network At the prompt type netstat nr g pi Callisto Pr pi Callisto Pi pifCallisto Pi pi Callisto Pi iwconfig wlang IEEE B02 11bq ESSID ReeveGCI Nickname lt WIFIG RE
37. o which you plan to connect You will need to determine iX SSID iX Password or key iX Encryption type and method for example WPA and TKIP shared key encryption Procedures for determining these parameters vary widely so you will need to refer to the wireless access point user guide or do online research The setup described in the following paragraphs assumes your Wi Fi network broadcasts the SSID Service Set Identifier See last page for copyright and document information File Reeve RPi LWATV doc Page 20 B 3 Setup W Fi Configuration Do not yet plug in the Wi Fi dongle Log into the RPi and enter the following commands sudo nano etc network interfaces z pi amp Callisto Pi GNU nano 2 2 6 amp tc network interfaces Buto lo iface lo inet loopback iface eth inet static address 10 0 0 11 netmask 255 255 255 10 network 10 0 0 0 broadcast 10 0 0 255 gateway 10 0 0 1 allow hotplug wlang iface wland inet dhcp wpa conf etc wpa supplicant wpa supplicant conf iface default inet dhcp Read 14 lines me Get Help ME WriteCut MS Read File fy Prey Page Wa Cut Text Jw Cur Pos ie a am Justify a Where Is ME Next Page WU UnCut Text To Spell i Note the following lines Do not change them auto lo iface lo inet loopback iface eth0 inet static The above form the basic wired network interface configuration in which the RPi uses a static IP address see Appendix A The lines that immediately foll
38. ow show the static IP configuration If your RPi is setup to use DHCP the third line of text will read as follows and there will be no addressing iface ethO0 inet dhcp Also note the following lines which provide basic WLAN configuration details Do not change them The WLAN configuration is defined by the wpa supplicant conf file allow hotplug wlanO0 iface wlanO inet dhcp wpa conf etc wpa supplicant wpa supplicant conf iface default inet dhcp Press CTRL X Exit to exit the nano editor It is necessary to edit the configuration file At the RPi prompt enter the following command sudo nano etc wpa supplicant wpa supplicant conf See last page for copyright and document information File Reeve RPi LWATV doc Page 21 z pi Callisto Pr GNU nano 2 2 6 ile etc wpa supplicant wpa supplicant cor Modified ctrl interface DIR var run wpa supplicant GROUP netdev update config 1 t To usa a wireless network uncomment the three lines below t Replace the fields in parentheses i network ssid WLAN i t psk My WLAN 1 Key f To use a wireless network uncomment the five lines below for proto key mgmt Protocol type can be RSN for WP2 and WPA for WPA1 ft Key management can be WPA PSE or WPA EAP Pre Shared or Enterprise f Pairwise can be CCMP or TEIP for WPA2 or WPA1 Authorization should be OPEN for both WPA1 WBA2 less common are SHARED and LS f Be sure to uncomment the closing brace proto WPA
39. ry Pi Foundation RPi The RPi is low cost about 35 USD 40 USD with memory card and has HDMI video Ethernet LAN and USB interfaces figure 3 It is euphemistically advertised as credit card size but actually is much larger It can be plugged into an ordinary computer monitor or TV and can use a WiFi wireless access device for LAN and internet access and wireless or wired USB keyboard and mouse Figure 3 Raspberry Pi model B and B hardware The model B is shown in the middle with an optional clear plastic enclosure The model B on the left is in an optional milled aluminum enclosure and is shown with a Bluetooth USB dongle The model B on the right is in a molded clear plastic enclosure and rotated to show the opposite end The interfaces vary slightly between the model B and B Enclosure dimensions are approximately 100 x 65 x 25 mm Image 2014 W Reeve The RPi hardware usually runs an operating system derived from Linux and as of this writing has become available in three versions original model A model not generally available in North America model B and model B The model B and B are compared table 1 For the LWA TV application there is no advantage of one over the other model See last page for copyright and document information File Reeve RPi LWATV doc Page 3 have not tried the RPi model A and initially could not get the LWA TV software image provided by UNM to work on the RPi B was successful only
40. s method requires removing the SD card from the RPi and then inserting it in a card reader connected to the Windows PC Be sure to shutdown the RPi before removing the memory card see next item Shutdown the RPi To avoid corrupting the RPi software the system must be properly shutdown before removing power just like a Windows PC This may be done from a keyboard connected to the RPi by pressing CTRL ALT F1 to invoke the console directly on the display or by using an SSH client on a PC Log into RPi at the prompts and then enter sudo shutdown h now Or sudo halt See last page for copyright and document information File Reeve RPi LWATV doc Page 13 The display will indicate the shutdown process All LED indicators except the red power LED on the RPi board will extinguish when the shutdown is complete Power may then be removed If you are at the console and change your mind before entering the shutdown commands press CTRL ALT F7 to return to LWA TV 6 References and Web Links 7 Zip http www 7 zip or Adafruit http www adafruit com LWA http www phys unm edu lwa index html LWA TV http www phys unm edu lwa Iwatv html LWA EPO http fornax phys unm edu Iwa trac wiki EPO LWASoft http fornax phys unm edu Iwa trac downloads Notepad http notepad plus plus or PuTTY http www putty or RPi http www raspberrypi or RPiDoc http www raspberrypi org documentation RPiHub http elinux org RPi
41. t find any RPi overscan settings that provided a properly positioned horizontal display Based on my experience so far think the video interface implementation is the RPi s biggest shortcoming the video implementation is separate from the LWA TV GUI Perhaps with enough time and experimentation could make it work better at different resolutions the si irsi GAA stati few seconds and if the isn t Y spe image updating right servations which we do for many hours every day Movie for September 6 2014 Copyright c 2014 The LWA Consortium T See last page for copyright and document information File Reeve RPi LWATV doc Page 11 Figure 11 Philips 47 in LCD television set connected through one of its HDMI ports to the RPi The RPi HDMI port was set for 720p resolution see text Image 2014 W Reeve As a final video test connected a Dynex 19 in LED LCD TV that use in the lab This is a small set designed as a kitchen counter TV with a wide range of video inputs After using the TV menu to select the HDMI port the screen immediately showed the correct display made no changes in the RPi video settings 720p used with the 47 in TV previously described Date time and time zone By default the Raspbian distribution uses Network Time Protocol NTP to automatically set the RPi time when it is connected to the internet The RPi does not have a real time clock or battery backup so it must be running and connected to th
42. ze electrical noise it is recommended that ferrite beads be installed on the power cable figure 5 Figure 5 AC wall power adapter with 5 V 2 4 A 12 W output purchased at BestBuy One or more clamshell ferrite beads on the dc power lead help reduce radio frequency interference from the switch mode power supply This image shows one bead on the right with three windings of the power lead The Raspberry Pi uses a micro USB connector for power Image 2014 W Reeve Software The RPi uses a software image that includes the operating system and applications The RPi image developed by UNM for the LWA TV GUI is based on a Raspbian distribution The software must be user installed on a memory card Installation is not difficult but it is done in a way that is not obvious to most Windows PC users UNM provides links to web pages with the necessary procedures see LWA EPO These procedures also are briefly listed in the Software installation part of section 5 To make this process a little simpler can provide a preprogrammed micro SD card in an SD card carrier to interested readers See Contact information at the end of this article With this memory card the system truly is plug and play When running the LWA TV GUI software the RPi can be used only for that purpose However the software is written in Python and may be modified by users if they feel adventurous Python is an interpreted language and therefore is not compiled so nothin
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