OE3GBB Hi Gerhard, I have not yet succesfully send CODEC2 data via DQPSK or even QPSK, even locally. I noticed that they use 15 (14+1) carriers instead of one that I trying. Is QO100 phase noise so high that it does not permit to use one high speed carrier ? It has been tested one high speed carrier in QO100?
MY QO100 SETUP
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Hi George,
Sorry, but I am not the right person to discuss that topic, I am just a tester.
As far I have understood, the sampling of the voice in codec2 is 20ms and 40ms for lower bitrate modes. So 50 Baud is a pretty good match for any type of modem. To get the whole coded data over the channel, David has used several carrieres in parallel and used OFDM to get them as close as possible. Any other modems would be maybe possible and there might be some information about the theory on freedv.org or http://www.rowetel.com.
In my view the easiest approach to get a best result regarding audio quality without neural network is to fill the 2700 kHz bandwith with as many carriers of 50 Baud. Using differential coding helps to reduce the BER.73's
Gerhard
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PA3FYM Hello Remco, this is my SWR plot of my POTY feeder. I do not see the second null near 2.4 GHz. Any comments ?
Interesting you don't ask me given I designed it... but anyway looking at the smith chart - it would be better to plot for 2.3-2.5 GHz but I think I can see the dual resonance looking like a ^ rather than a loop. Should be good enough though you have all the tools to get it spot on.
Mike
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That looks excellent.
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Good morning George, I saw the notification of the message on my e-mail ok good test just yesterday I did some practice on the directional couplers. My good transverter I have to make an attenuator from 500 milliwatt to 1milliwatt in input if tx the pi attenuation calculated 27 db of attenuation two 56 hom resistors and one 560 i resistor but to be able to vary I have to put a 1khom trimmer in replacement 560 h resistor correct?
Thanks
Roberto
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here is the photo of my tx 2.4 and rx 739/436 mhz transverter
Roberto iw5bsf
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iw5bsf I have done something similar. You are right about the values. The critical is the ground paths of the two 56 ohm resistors. If they have inductance to the ground the actual attenuation will be smaller. To avoid high power passing I replaced variable R with a fixed one. Also use metal film or carbon for all as the usual resistors are inductive. I have also the W1GHZ 2.4 GHz transverter and begin assemby it for simplex usage.
Thank George, I put 560 hom fixed as indicated by the 5% tolerance of metal oxide that I tried before measuring the measured power ft87 on 27.7 dbm then inserted the attenuator (26.8 db considering the tolerance of the resistors) at the output = 0.90 is ok
73 de iw5bsf Roberto
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Hi,
I plan to buy a Prologix GPIB Ethernet adapter. Any suggestions ?
I did the same a couple of years ago. They are a.f.a.i.k. not compatible with software from NI, or Matlab. So you have to write your own code.
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Hi,
I plan to buy a Prologix GPIB Ethernet adapter. Any suggestions ?
Hi,
Depends on the measuring application. I use Prologix GPIB about 5 years. I had both - NI and Prologix. Prologix works great for me with the R&S FSQ8 for measuring phase noise and with Pendulum CNT-91 for measuring Allan deviation. NI has been sold as he did no more in the applications I needed.
73 de Karen, ra3apw
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Sorry, my Prologix version is GPIB-USB, not GPIB-Ethernet.
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Hi, thanks for the answers. My plans are to write my own Python scripts. Also to use 7470.exe as plotter emulator. At this Link it has software that can be used. My thought about Ethernet is that it will be available from any PC local or remote. Applications ideas are phase noise, alan deviation, real time web spectrum monitor of HF-UHF.
Hi George,
look at TimeLab from John Miles, KE5FX http://www.miles.io/timelab/readme.htm and http://www.ke5fx.com/gpib/pn.htm.
It seems you can find most of your wishes there including Prologix GPIB (both versions GPIB-USB/GPIB-Ethernet) support http://www.ke5fx.com/gpib/readme.htm#prologix.
73 de Karen, ra3apw
