[digitalradio] Re: Testing Digital Codes at Bit Level
Hi Rud. I do not know any program, that introduces errors into bit stream for protocol tuning purposes. For tuning the decoders in PocketDigi, I used Moe's WSCGen, which generates test streams of various levels of AWGN. http://www.moetronix.com/ae4jy/projects.htm It is not valid to simulate AWGN in bit stream by flipping bits. All the advanced decoders use soft bits technique, that works with fuzzy bits. For example, MFSK16 decoder utilizing Viterbi decoder implemented by Phil Karn KA9Q and used by gMFSK, fldigi and PocketDigi reads bits quantized to 8 bits, 0 signalizing 100% zero, 255 siganlizing 100% one and 127 dont't know. Noise may influence not only data stream, but also its synchronization in time and frequency (AFC). At the end, one needs to evaluate the whole decoder chain at once. One phase error in differential system (psk31, domino) caused by noise may introduce two successive bit errors. One error in FSK system will introduce only one bit error. Fading: is it valid to simulate fading by removing some bits in the data stream? It depends on the coding and synchronization. If the code is synchronous and sync lock is slow, it may survive the fading gap. Then you will get a correct number of bits, which will contain rubbish. An asynchronous decoder like RTTY will soon be lost, throwing away whole 6-bit symbols. 73, Vojtech
Re: [digitalradio] USB devices with Linux/FreeBSD
http://forums.ham-radio.ch/archive/index.php?t-3399.html here is a link to a discussion a year ago. 2006. seems like the command set is open but the interfacing code is alot of work for the RixExpert On 11/5/07, Rem Roberti [EMAIL PROTECTED] wrote: Has anyone had any success using a USB device such as RixExpert on either the Linux or FreeBSD platforms? I have been using the RixExpert for a couple of years with Windows, but have not been able to successfully get it work on other platforms. Rem W6REM
[digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
I believe that if you are licensed by the fcc, you must obey fcc rules and regulations when operating in international waters. Only when you reach national waters do foreign rules and regs come into play. Jim WA0LYK --- In digitalradio@yahoogroups.com, Russell Hltn [EMAIL PROTECTED] wrote: On Nov 5, 2007 6:59 PM, Phil Barnett [EMAIL PROTECTED] wrote: On Monday 05 November 2007, Rick Karlquist wrote: FCC part 97.203d says that this frequency (10.123) is not authorized for automatically controlled beacon stations. It is not clear that this balloon is under any kind of manual control. I see that telemetry is an OK 1 way transmission 97.111.b.7, but there is the question of control. Maybe someone can educate me how this is legal. I doubt that the FCC has jurisdiction over the Atlantic Ocean airspace. What callsign will it be using? Will it stay silent until it's in international waters?
[digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
Looks to me like it should be operating on 28.2028.30 MHz according to 97.203d. Also, if the balloons path goes over the National Radio Quiet Zone, 97.203(e)/97.3(a)(30) it looks like permission is supposed to be obtained. Lastly, does foreign operation come into play and the need for reciprocal licenses when the balloon reaches Europe? Jim WA0LYK --- In digitalradio@yahoogroups.com, Rick Karlquist [EMAIL PROTECTED] wrote: Mark Thompson wrote: - Forwarded Message From: John [EMAIL PROTECTED] Sent: Monday, November 5, 2007 4:50:26 PM Subject: Balloon Launch 10 MHz Amateur Radio balloon to cross the Atlantic The balloon payload will include a GPS unit and CPU that will regulate the balloon's altitude and send telemetry on 10.123 MHz in CW and RTTY formats. The 10 MHz transmitter will run 3 watts output into a half wave dipole hung below the balloon. FCC part 97.203d says that this frequency (10.123) is not authorized for automatically controlled beacon stations. It is not clear that this balloon is under any kind of manual control. I see that telemetry is an OK 1 way transmission 97.111.b.7, but there is the question of control. Maybe someone can educate me how this is legal. Rick N6RK
[digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
TNX for the info. I think you should post the message again when the baloon is on it's way. Or just a reminder so i wont forget to listen-in. I think it's a very intresting experiment lasting only a few days. So i personally dont understand the attitude of interpreting the national us band regulations against it...
Re: [digitalradio] Testing Digital Codes at Bit Level
Hi Rud, I just sent you the Pascal source code for generating and receiving OFDM via wav files. There is also a simple program that will modify a file to simulate multipath by converting it into multiple rays. I agree with Vojtech that it's not very useful to flip bits for testing as any useful decoder for HF will operate on an analog input with a resolution at least 2 bits greater than the number of bits encoded in the transmitted signal. 73, John KD6OZH - Original Message - From: Rud Merriam To: digitalradio@yahoogroups.com Sent: Tuesday, November 06, 2007 02:48 UTC Subject: [digitalradio] Testing Digital Codes at Bit Level I would like to test some digital codes at the bit level, rather than the audio level. Does anyone know of a program that will introduce noise by changing bits in a bit stream? Is anyone familiar with any published works on the web that discuss testing at this level? --- I have a feeling that the above questions are not going to be answered so lets try the roll my own approach for AWGN and Fading in the first attempt. Gaussian Noise: is it valid to generate a stream of noise bits where exceeding a threshold amplitude level injects an erroneous bit into the data stream? I am assuming that noise cannot remove a bit but is that a valid assumption? Fading: is it valid to simulate fading by removing some bits in the data stream? Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net
RE: [digitalradio] Testing Digital Codes at Bit Level
I understand about the use of soft decoders. If the protocol uses a soft decoder and another hard decoder the latter works at the bit level. A standard example is using Reed-Solomon for the hard decoder. Would the bit flipping be representative of the atmospheric effects for the outer hard decoder, e.g. RS decoder? Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net http://thehamnetwork.net/
Re: [digitalradio] Testing Digital Codes at Bit Level
If you have an inner and outer code that would be the situation, but I'm not sure that flipping one bit would always be accurate. A Viterbi decoder might generate small bursts of errors. HDTV uses TCM with an outer Reed-Solomon code. Even though there are 12 interleaved convolutional encoders, they still use an RS code that is capable of correcting bursts of 8 errors. 73, John KD6OZH - Original Message - From: Rud Merriam To: digitalradio@yahoogroups.com Sent: Tuesday, November 06, 2007 20:10 UTC Subject: RE: [digitalradio] Testing Digital Codes at Bit Level I understand about the use of soft decoders. If the protocol uses a soft decoder and another hard decoder the latter works at the bit level. A standard example is using Reed-Solomon for the hard decoder. Would the bit flipping be representative of the atmospheric effects for the outer hard decoder, e.g. RS decoder? Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net
Re: [digitalradio] 10 MHz Amateur Radio balloon to Cross the Atlantic
I believe it falls, jurisdictionwise, in the same case as a satellite. It must be licensed by some administration, and also, do not violate the spectrum boundaries of others under it. That is cleat on the satellite bands, but not so in HF, in a non satellite activity allocated band. Jose, CO2JA. --- Phil Barnett escribió: On Monday 05 November 2007, Rick Karlquist wrote: FCC part 97.203d says that this frequency (10.123) is not authorized for automatically controlled beacon stations. It is not clear that this balloon is under any kind of manual control. I see that telemetry is an OK 1 way transmission 97.111.b.7, but there is the question of control. Maybe someone can educate me how this is legal. I doubt that the FCC has jurisdiction over the Atlantic Ocean airspace. __ Participe en Universidad 2008. 11 al 15 de febrero del 2008. Palacio de las Convenciones, Ciudad de la Habana, Cuba http://www.universidad2008.cu
Re: [digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
Russell Hltn wrote: I personally have nothing against them, but they do need to follow the law. One would think the space program would have settled all of these questions already. Legally, it is not a spacecraft because it is less than 50 km high. Rick N6RK
Re: [digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
On Nov 6, 2007 5:02 AM, cesco12342000 [EMAIL PROTECTED] wrote: I think it's a very intresting experiment lasting only a few days. So i personally dont understand the attitude of interpreting the national us band regulations against it... If it's not done right it sets a bad precedent. I personally have nothing against them, but they do need to follow the law. One would think the space program would have settled all of these questions already.
Re: [digitalradio] 10 MHz Amateur Radio balloon to Cross the Atlantic
That's right. I was only referring to the radio aspects, and did not account for that thing classifying as an aircraft. It may easily become a navigation hazard. Complicated, and ugly indeed... Jose, CO2JA --- John B. Stephensen escribió: Anything less than 50 km in altitude is an aircraft and must be licensed by the country of origin while it's over international waters and by the country it's flying over when over land. 73, John KD6OZH - Original Message - *From:* Jose Amador mailto:[EMAIL PROTECTED] *To:* digitalradio@yahoogroups.com mailto:digitalradio@yahoogroups.com *Sent:* Tuesday, November 06, 2007 22:33 UTC *Subject:* Re: [digitalradio] 10 MHz Amateur Radio balloon to Cross the Atlantic I believe it falls, jurisdictionwise, in the same case as a satellite. It must be licensed by some administration, and also, do not violate the spectrum boundaries of others under it. That is cleat on the satellite bands, but not so in HF, in a non satellite activity allocated band. Jose, CO2JA. __ Participe en Universidad 2008. 11 al 15 de febrero del 2008. Palacio de las Convenciones, Ciudad de la Habana, Cuba http://www.universidad2008.cu
[digitalradio] Re: 10 MHz Amateur Radio balloon to Cross the Atlantic
I have posted this on the mailing list of Icelandic Radio Amateur club. Hopefully someone there might have an interest. 73 de TF3AO Seli --- In digitalradio@yahoogroups.com, Mark Thompson [EMAIL PROTECTED] wrote: - Forwarded Message From: John [EMAIL PROTECTED] Sent: Monday, November 5, 2007 4:50:26 PM Subject: Balloon Launch 10 MHz Amateur Radio balloon to cross the Atlantic Amateurs at the University of Tennessee Amateur Radio Club are launching a balloon with a beacon in the 10 MHz Amateur Band that may travel across the Atlantic during its 5-day mission. The latest Icarus X mission UX-19, will hopefully launch by next weekend and its goal is to be the first Amateur Radio equiped helium balloon to cross the Atlantic. The balloon payload will include a GPS unit and CPU that will regulate the balloon's altitude and send telemetry on 10.123 MHz in CW and RTTY formats. The 10 MHz transmitter will run 3 watts output into a half wave dipole hung below the balloon. The students need receiving stations to copy the telemetry data. They have developed a decoding program that anyone can download from the University of Tennessee web site which will relay the values back to the campus server. All that is needed for the receiving station is a good antenna and a computer with a high speed internet connection. Audio from the receiver is feed into the sound card of the computer and Mtty will decode the values and give a nice visual status page of the flight data. Also the data will be sent to the University of Tennessee's server where it will be placed onto the club's web page for everyone to follow. The flight has been dubbed 'The Spirit Of Knoxville' after Lindbergh's first trans-Atlantic flight. The flight could be up to a five days long but the actual crossing should take only three days. The balloon will be carrying enough ballast and battery power for five days and nights. Check the UT Radio Club's web page at http://www.utarc.org/ for more technical details and a host of photos. This site chronicles the last years worth of effort at developing the hardware and flight testing the different systems to produce an autonomous altitude control. In addition to the 30m beacon there will also be an APRS beacon AA4UT-11 on 144.390 MHz FM. University of Tennessee Amateur Radio Club http://www.utarc.org/ If you go to their website and click on the Balloon Launch link right above the article you'll go to a page with a neat You Tube video of a previous launch. 73, John - AG9D __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: [digitalradio] 10 MHz Amateur Radio balloon to Cross the Atlantic
On Nov 6, 2007 3:07 PM, Jose Amador [EMAIL PROTECTED] wrote: That's right. I was only referring to the radio aspects, and did not account for that thing classifying as an aircraft. It may easily become a navigation hazard. Complicated, and ugly indeed... There are standard protocols for dealing with that. As long as someone in the group has done their homework to make sure it complies, there's no issue.
RE: [digitalradio] Testing Digital Codes at Bit Level
In addition, if you have a systematic code versus convolutional or trellis encoding is the bit flipping not applicable? One of my other research activities is on Low Density Parity Codes since they approach channel capacity better than other codes. Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net http://thehamnetwork.net/ -Original Message- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of John B. Stephensen Sent: Tuesday, November 06, 2007 2:30 PM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] Testing Digital Codes at Bit Level If you have an inner and outer code that would be the situation, but I'm not sure that flipping one bit would always be accurate. A Viterbi decoder might generate small bursts of errors. HDTV uses TCM with an outer Reed-Solomon code. Even though there are 12 interleaved convolutional encoders, they still use an RS code that is capable of correcting bursts of 8 errors. 73, John KD6OZH - Original Message - From: Rud Merriam mailto:[EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Tuesday, November 06, 2007 20:10 UTC Subject: RE: [digitalradio] Testing Digital Codes at Bit Level I understand about the use of soft decoders. If the protocol uses a soft decoder and another hard decoder the latter works at the bit level. A standard example is using Reed-Solomon for the hard decoder. Would the bit flipping be representative of the atmospheric effects for the outer hard decoder, e.g. RS decoder? Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwor http://thehamnetwork.net/ k.net
[digitalradio] 30m Digital QRP Weekend Nov 10th 11th
Please join us November 10th utc to 11th 2400utc for 30 Meter Digital QRP Weekend to promote 30m PSK 10.140 +/-1000 and other digital modes (MFSK,OLIVIA,HELL,RTTY,etc wider modes 10.135 to 10.142) This is NOT a contest but a group event to promote 30 meter digital activity and awareness: testing of band propagation with low power, different types antennas, ragchew, dx contacts using low power, experimenting of different digital weaksignal soundcard modes/power/antennas, etc etc stations may call CQ followed by CALLSIGN/QRP/Wattage i.e. CQ CQ CQ KB9UMT/QRP/1W to let others know right away wattage or CALLSIGN/QRP FB also, reports to spot page or group welcome. Let's get on the air and have some digital fun and get others to notice our only low power, digital only, and no contest band of 30 meters! See you on the waterfall! de kb9umt Don EN50dp http://groups.yahoo.com/group/30meterPSKGroup/ use the 30m spot page-thanks Sholto http://www.projectsandparts.com/30m/
Re: [digitalradio] Testing Digital Codes at Bit Level
Convolutional or trellis codes work by forcing specific sequences of state transitions and detecting errors when those transitions don't happen. Once the decoder makes an error it could take several symbols get get back into synchronization with the transmitter. If you mean the systematic (feedback free) form of a convolutional encoder it has the same limitations as the form using feedback as they generate the same encoded output. If you mean a block code like LDPC, Golay or Walsh codes, errors don't propogate beyond the block. From what I've read, turbo codes get very close to channel capacity but they require very long block lengths (greater than 10,000 symbols) and an iterative decoder to be effective. 73, John KD6OZH - Original Message - From: Rud Merriam To: digitalradio@yahoogroups.com Sent: Wednesday, November 07, 2007 02:24 UTC Subject: RE: [digitalradio] Testing Digital Codes at Bit Level In addition, if you have a systematic code versus convolutional or trellis encoding is the bit flipping not applicable? One of my other research activities is on Low Density Parity Codes since they approach channel capacity better than other codes. Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net -Original Message- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of John B. Stephensen Sent: Tuesday, November 06, 2007 2:30 PM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] Testing Digital Codes at Bit Level If you have an inner and outer code that would be the situation, but I'm not sure that flipping one bit would always be accurate. A Viterbi decoder might generate small bursts of errors. HDTV uses TCM with an outer Reed-Solomon code. Even though there are 12 interleaved convolutional encoders, they still use an RS code that is capable of correcting bursts of 8 errors. 73, John KD6OZH - Original Message - From: Rud Merriam To: digitalradio@yahoogroups.com Sent: Tuesday, November 06, 2007 20:10 UTC Subject: RE: [digitalradio] Testing Digital Codes at Bit Level I understand about the use of soft decoders. If the protocol uses a soft decoder and another hard decoder the latter works at the bit level. A standard example is using Reed-Solomon for the hard decoder. Would the bit flipping be representative of the atmospheric effects for the outer hard decoder, e.g. RS decoder? Rud Merriam K5RUD ARES AEC Montgomery County, TX http://TheHamNetwork.net
