Re: [Freetel-codec2] codec2 modes and sm1000 PTT

[Brady O'Brien]

Faisal,

I've not yet done any work to port 2400A or 2400B to the SM1000 or STM32F4.
The FMFSK modem used by 2400B will probably run without issue, as it
doesn't use a whole lot of memory as is, but I'm not sure about FSK. The
big issue I see for you is that 2400A and 2400B operate at a 48Khz sample
rate instead of the 8Khz rate of 1600 or 7.5/8Khz rate of 700B. You'll also
need to move the 2400A/B initialization outside of the #ifdefs in
freedv_api.c for it to build to the SM1000.

Thanks,

Brady O'Brien

On Thu, Mar 17, 2016 at 2:01 PM, David Rowe  wrote:

> Hi Faisal,
>
> 1/ You need to change the protocol, bit packing, FEC, number of tones
> etc.  There may be CPU load issues.  Suggest you start with the Host PC
> version and test there.  Get the entire system working fine on a PC
> first, then try porting to the SM1000.
>
> 2/ Edit sm1000_main.c where PTT is pressed?  Maybe use a state machine
> to inject a compressed Codec 2 message before taking audio from the
> microphone.
>
> - David
>
> On 17/03/16 22:39, Faisal Saleem wrote:
> >
> > Hi all,
> >   I am an engineering student and working on a digital voice project. I
> am impressed by codec2 and sm1000, the freedv adapter. I just got 2 sm1000
> modules and built the firmware sm1000.bin successfully. I connected the two
> sm1000 boards back to back using RIG interface (a cross RJ45 cable). And
> both sm1000 are talking to each other both in analog and DV modes
> (fantastic). While studying the code, I've seen that the codec 2 mode is
> set to 1300. I just changed the codec2 mode to 1600. At 1600 mode the voice
> quality was not very good compared to 1300 mode and also there was a bit
> error (error LED constantly on). When I just set the mode to 2400, receiver
> doesn't receive any thing while transmitter is transmitting. My questions
> are:
> > 1) Is it enough to change the codec mode in freedvapi.c to change the
> codec mode or do I need to change some other parameters like Nc, NB etc to
> run it on 2400 mode without any BER.
> > 2) I want to access the PTT i.e. whenever I press PTT, I want to
> transmit a custom message first before transmitting the actual voice. How I
> can do this?
> >
> > Thanks in advance for your precious help.
> >
> > Regards,
> > Faisal
> >
> >
> --
> > Transform Data into Opportunity.
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> > Intel Data Analytics Acceleration Library.
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> >
>
>
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Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[Adrian Musceac]

Hi Brady, David,

Thank you very much for sharing the GRC flowgraphs. This will help me
a lot setting up a similar test. Regarding the performance, I was just
surprised to see such a big difference between a modem which runs
through analog FM and your new modem. I would have expected something
in the range of 6-10 dB, not 16-20 dB. Maybe I need to calibrate my
signal again.
I enjoyed a lot reading about the experiment on your blog David. It
seems like a new revolution for VHF/UHF weak signal work.

73,
Adrian (YO8RZZ)

On 3/17/16, Brady O'Brien  wrote:
> Hey Adrian,
>
> The gnuradio-companion pipelines I used for the test are attached. These
> grc pipelines are only meant to get 16-bit 48k samples in and out of the
> HackRF and rtlsdr for testing. The meat of the FSK is done with the C fsk
> modem, used in freedv_rx, freedv_tx, fsk_mod, and fsk_demod. We are also
> running our FSK modem directly from SDR samples instead of through FM
> radios. We will be running 2400B over legacy FM radios, but don't yet have
> the same degree of test coverage.
>
> Thanks,
>
> Brady O'Brien
>
> On Wed, Mar 16, 2016 at 3:34 PM, Adrian Musceac  wrote:
>
>> Hi David,
>>
>> Is it possible to get our hands on the Gnuradio code? I've been trying
>> to optimize modems running at 1200 bits/second and the best I could do
>> was 100% copy at 8 dB above analog FM for DBPSK and 12 dB above for
>> GMSK. Your modem seems to be 16-20 dB better than that! If I could see
>> the Gnuradio graph maybe I could figure out what I'm doing wrong.
>>
>> Thanks,
>> Adrian
>>
>> On 3/16/16, Steve  wrote:
>> > Ha, I wish it was through a radio!
>> >
>> > I'm trying to think what I have laying around here that might make a
>> > good
>> > transmitter for it.
>> >
>> > On Wed, Mar 16, 2016 at 4:02 AM, glen english 
>> wrote:
>> >
>> >> ah. good stuff. nice progress.
>> >>
>> >>
>> >> On 16/03/2016 7:50 PM, Steve wrote:
>> >>
>> >> Just using the script:
>> >>
>> >> freedv_tx 2400A ve9qrp_10s.raw modem.raw
>> >>
>> >> Which produces a RAW audio file sampled at 48 kHz and importing that
>> into
>> >> audacity.
>> >>
>> >> On Wed, Mar 16, 2016 at 3:46 AM, glen english 
>> >> wrote:
>> >>
>> >>> Hi Steve
>> >>>
>> >>> Nice
>> >>>
>> >>> is that through a PA- if so, linear or linear in say 3dB compression?
>> >>>
>> >>>
>> >>> On 16/03/2016 7:42 PM, Steve wrote:
>> >>>
>> >>> Thought I'd upload a spectrum snapshot. You can't really see the
>> >>> carriers
>> >>> until you drop the number of samples to about 256, but this shows how
>> >>> wide
>> >>> it is.
>> >>>
>> >>> I noticed that the freedv_tx was outputting +/- 1.0 signals and a
>> couple
>> >>> of clips going on. Maybe need to knock it down to +/- .5 like the old
>> >>> FDM
>> >>> modes.
>> >>>
>> >>> FYI
>> >>>
>> >>> Steve
>> >>>
>> >>>
>> >>>
>> >>>
>> --
>> >>> Transform Data into Opportunity.
>> >>> Accelerate data analysis in your applications with
>> >>> Intel Data Analytics Acceleration Library.
>> >>> Click to learn
>> >>> more.http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
>> >>>
>> >>>
>> >>>
>> >>> ___
>> >>> Freetel-codec2 mailing
>> >>> listFreetel-codec2@lists.sourceforge.nethttps://
>> lists.sourceforge.net/lists/listinfo/freetel-codec2
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> --
>> >>> Transform Data into Opportunity.
>> >>> Accelerate data analysis in your applications with
>> >>> Intel Data Analytics Acceleration Library.
>> >>> Click to learn more.
>> >>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
>> >>> ___
>> >>> Freetel-codec2 mailing list
>> >>> Freetel-codec2@lists.sourceforge.net
>> >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
>> >>>
>> >>>
>> >>
>> >>
>> >>
>> --
>> >> Transform Data into Opportunity.
>> >> Accelerate data analysis in your applications with
>> >> Intel Data Analytics Acceleration Library.
>> >> Click to learn
>> >> more.http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
>> >>
>> >>
>> >>
>> >> ___
>> >> Freetel-codec2 mailing
>> >> listFreetel-codec2@lists.sourceforge.nethttps://
>> lists.sourceforge.net/lists/listinfo/freetel-codec2
>> >>
>> >>
>> >>
>> >>
>> >>
>> --
>> >> Transform Data into Opportunity.
>> >> Accelerate data analysis in your applications with
>> >> Intel Data Analytics Acceleration Library.
>> >> Click to learn more.
>> >> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
>> >> ___

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[Brady O'Brien]

Hey Adrian,

The gnuradio-companion pipelines I used for the test are attached. These
grc pipelines are only meant to get 16-bit 48k samples in and out of the
HackRF and rtlsdr for testing. The meat of the FSK is done with the C fsk
modem, used in freedv_rx, freedv_tx, fsk_mod, and fsk_demod. We are also
running our FSK modem directly from SDR samples instead of through FM
radios. We will be running 2400B over legacy FM radios, but don't yet have
the same degree of test coverage.

Thanks,

Brady O'Brien

On Wed, Mar 16, 2016 at 3:34 PM, Adrian Musceac  wrote:

> Hi David,
>
> Is it possible to get our hands on the Gnuradio code? I've been trying
> to optimize modems running at 1200 bits/second and the best I could do
> was 100% copy at 8 dB above analog FM for DBPSK and 12 dB above for
> GMSK. Your modem seems to be 16-20 dB better than that! If I could see
> the Gnuradio graph maybe I could figure out what I'm doing wrong.
>
> Thanks,
> Adrian
>
> On 3/16/16, Steve  wrote:
> > Ha, I wish it was through a radio!
> >
> > I'm trying to think what I have laying around here that might make a good
> > transmitter for it.
> >
> > On Wed, Mar 16, 2016 at 4:02 AM, glen english 
> wrote:
> >
> >> ah. good stuff. nice progress.
> >>
> >>
> >> On 16/03/2016 7:50 PM, Steve wrote:
> >>
> >> Just using the script:
> >>
> >> freedv_tx 2400A ve9qrp_10s.raw modem.raw
> >>
> >> Which produces a RAW audio file sampled at 48 kHz and importing that
> into
> >> audacity.
> >>
> >> On Wed, Mar 16, 2016 at 3:46 AM, glen english 
> >> wrote:
> >>
> >>> Hi Steve
> >>>
> >>> Nice
> >>>
> >>> is that through a PA- if so, linear or linear in say 3dB compression?
> >>>
> >>>
> >>> On 16/03/2016 7:42 PM, Steve wrote:
> >>>
> >>> Thought I'd upload a spectrum snapshot. You can't really see the
> >>> carriers
> >>> until you drop the number of samples to about 256, but this shows how
> >>> wide
> >>> it is.
> >>>
> >>> I noticed that the freedv_tx was outputting +/- 1.0 signals and a
> couple
> >>> of clips going on. Maybe need to knock it down to +/- .5 like the old
> >>> FDM
> >>> modes.
> >>>
> >>> FYI
> >>>
> >>> Steve
> >>>
> >>>
> >>>
> >>>
> --
> >>> Transform Data into Opportunity.
> >>> Accelerate data analysis in your applications with
> >>> Intel Data Analytics Acceleration Library.
> >>> Click to learn
> >>> more.http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> >>>
> >>>
> >>>
> >>> ___
> >>> Freetel-codec2 mailing
> >>> listFreetel-codec2@lists.sourceforge.nethttps://
> lists.sourceforge.net/lists/listinfo/freetel-codec2
> >>>
> >>>
> >>>
> >>>
> >>>
> --
> >>> Transform Data into Opportunity.
> >>> Accelerate data analysis in your applications with
> >>> Intel Data Analytics Acceleration Library.
> >>> Click to learn more.
> >>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> >>> ___
> >>> Freetel-codec2 mailing list
> >>> Freetel-codec2@lists.sourceforge.net
> >>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
> >>>
> >>>
> >>
> >>
> >>
> --
> >> Transform Data into Opportunity.
> >> Accelerate data analysis in your applications with
> >> Intel Data Analytics Acceleration Library.
> >> Click to learn
> >> more.http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> >>
> >>
> >>
> >> ___
> >> Freetel-codec2 mailing
> >> listFreetel-codec2@lists.sourceforge.nethttps://
> lists.sourceforge.net/lists/listinfo/freetel-codec2
> >>
> >>
> >>
> >>
> >>
> --
> >> Transform Data into Opportunity.
> >> Accelerate data analysis in your applications with
> >> Intel Data Analytics Acceleration Library.
> >> Click to learn more.
> >> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> >> ___
> >> Freetel-codec2 mailing list
> >> Freetel-codec2@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
> >>
> >>
> >
>
>
> --
> Transform Data into Opportunity.
> Accelerate data analysis in your applications with
> Intel Data Analytics Acceleration Library.
> Click to learn more.
> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> ___
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> Freetel-codec2@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
>


rtlsdr-rx.grc
Description: application/gnuradio-grc


hackrf-tx.grc
Description: 

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[David Rowe]

Hi Adrian,

I think Brady's going to get back you with his GR code.  Not sure if the 
FSK modem is still outboard of GR, or if he has a GR module for it.

Note we are not running our modems through the analog FM 
modulator/demodulator, as that's how you throw perfectly good dB away. 
I'm looking at you DSTAR, DRM, and C4FM.

Heaps of my blog posts on this topic over the last 18 months.

Cheers,

David

On 17/03/16 07:04, Adrian Musceac wrote:
> Hi David,
>
> Is it possible to get our hands on the Gnuradio code? I've been trying
> to optimize modems running at 1200 bits/second and the best I could do
> was 100% copy at 8 dB above analog FM for DBPSK and 12 dB above for
> GMSK. Your modem seems to be 16-20 dB better than that! If I could see
> the Gnuradio graph maybe I could figure out what I'm doing wrong.
>
> Thanks,
> Adrian
>
> On 3/16/16, Steve  wrote:
>> Ha, I wish it was through a radio!
>>
>> I'm trying to think what I have laying around here that might make a good
>> transmitter for it.
>>
>> On Wed, Mar 16, 2016 at 4:02 AM, glen english  wrote:
>>
>>> ah. good stuff. nice progress.
>>>
>>>
>>> On 16/03/2016 7:50 PM, Steve wrote:
>>>
>>> Just using the script:
>>>
>>> freedv_tx 2400A ve9qrp_10s.raw modem.raw
>>>
>>> Which produces a RAW audio file sampled at 48 kHz and importing that into
>>> audacity.
>>>
>>> On Wed, Mar 16, 2016 at 3:46 AM, glen english 
>>> wrote:
>>>
 Hi Steve

 Nice

 is that through a PA- if so, linear or linear in say 3dB compression?


 On 16/03/2016 7:42 PM, Steve wrote:

 Thought I'd upload a spectrum snapshot. You can't really see the
 carriers
 until you drop the number of samples to about 256, but this shows how
 wide
 it is.

 I noticed that the freedv_tx was outputting +/- 1.0 signals and a couple
 of clips going on. Maybe need to knock it down to +/- .5 like the old
 FDM
 modes.

 FYI

 Steve



 --
 Transform Data into Opportunity.
 Accelerate data analysis in your applications with
 Intel Data Analytics Acceleration Library.
 Click to learn
 more.http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140



 ___
 Freetel-codec2 mailing
 listFreetel-codec2@lists.sourceforge.nethttps://lists.sourceforge.net/lists/listinfo/freetel-codec2




 --
 Transform Data into Opportunity.
 Accelerate data analysis in your applications with
 Intel Data Analytics Acceleration Library.
 Click to learn more.
 http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
 ___
 Freetel-codec2 mailing list
 Freetel-codec2@lists.sourceforge.net
 https://lists.sourceforge.net/lists/listinfo/freetel-codec2


>>>
>>>
>>> --
>>> Transform Data into Opportunity.
>>> Accelerate data analysis in your applications with
>>> Intel Data Analytics Acceleration Library.
>>> Click to learn
>>> more.http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
>>>
>>>
>>>
>>> ___
>>> Freetel-codec2 mailing
>>> listFreetel-codec2@lists.sourceforge.nethttps://lists.sourceforge.net/lists/listinfo/freetel-codec2
>>>
>>>
>>>
>>>
>>> --
>>> Transform Data into Opportunity.
>>> Accelerate data analysis in your applications with
>>> Intel Data Analytics Acceleration Library.
>>> Click to learn more.
>>> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
>>> ___
>>> Freetel-codec2 mailing list
>>> Freetel-codec2@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
>>>
>>>
>>
>
> --
> Transform Data into Opportunity.
> Accelerate data analysis in your applications with
> Intel Data Analytics Acceleration Library.
> Click to learn more.
> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> ___
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> Freetel-codec2@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/freetel-codec2
>

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Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[Bruce Perens]

Did I hear that right? Works with non linear amplifiers, competitive with
SSB, replaces all your multi carrier modems?

On Thu, Mar 17, 2016, 11:51 David Rowe  wrote:

> Hi Adrian,
>
> Getting the modem right can be really critical.  It's good that we are
> discovering this and talking about it in Ham and open source circles,
> and getting high quality modem code out there.
>
> I learned about modems in the sat-com industry.  As the satellites are
> expensive, we would try to get our modems to within 0.25dB of theory.
> Otherwise we were just wasting mega-$.
>
> It still puzzles me why something like DMR has deliberately chosen a
> modem waveform (with less than Rs Hz spacing tones) that hobbles the
> system by 6dB.  The power being wasted is like throwing away 3/4 of your
> HT battery.
>
> Suspect of your 16dB loss is a measurement error or perhaps the FM modem
> is not set up right.  I found simulating analog FM and getting
> performance like the text books to be surprisingly difficult:
>
>http://www.rowetel.com/blog/?p=3799
>
> Maybe you could first test your FM modem, see if you can get the C/No
> input versus SNR out curve.
>
> Looking forward, FreeDV 2400A is competitive with SSB for weak signal
> work today, and I think we can push down another 10dB over time.
>
> Cheers,
>
> David
>
> On 17/03/16 23:11, Adrian Musceac wrote:
> > Hi Brady, David,
> >
> > Thank you very much for sharing the GRC flowgraphs. This will help me
> > a lot setting up a similar test. Regarding the performance, I was just
> > surprised to see such a big difference between a modem which runs
> > through analog FM and your new modem. I would have expected something
> > in the range of 6-10 dB, not 16-20 dB. Maybe I need to calibrate my
> > signal again.
> > I enjoyed a lot reading about the experiment on your blog David. It
> > seems like a new revolution for VHF/UHF weak signal work.
> >
> > 73,
> > Adrian (YO8RZZ)
> >
> > On 3/17/16, Brady O'Brien  wrote:
> >> Hey Adrian,
> >>
> >> The gnuradio-companion pipelines I used for the test are attached. These
> >> grc pipelines are only meant to get 16-bit 48k samples in and out of the
> >> HackRF and rtlsdr for testing. The meat of the FSK is done with the C
> fsk
> >> modem, used in freedv_rx, freedv_tx, fsk_mod, and fsk_demod. We are also
> >> running our FSK modem directly from SDR samples instead of through FM
> >> radios. We will be running 2400B over legacy FM radios, but don't yet
> have
> >> the same degree of test coverage.
> >>
> >> Thanks,
> >>
> >> Brady O'Brien
> >>
> >> On Wed, Mar 16, 2016 at 3:34 PM, Adrian Musceac 
> wrote:
> >>
> >>> Hi David,
> >>>
> >>> Is it possible to get our hands on the Gnuradio code? I've been trying
> >>> to optimize modems running at 1200 bits/second and the best I could do
> >>> was 100% copy at 8 dB above analog FM for DBPSK and 12 dB above for
> >>> GMSK. Your modem seems to be 16-20 dB better than that! If I could see
> >>> the Gnuradio graph maybe I could figure out what I'm doing wrong.
> >>>
> >>> Thanks,
> >>> Adrian
> >>>
> >>> On 3/16/16, Steve  wrote:
>  Ha, I wish it was through a radio!
> 
>  I'm trying to think what I have laying around here that might make a
>  good
>  transmitter for it.
> 
>  On Wed, Mar 16, 2016 at 4:02 AM, glen english 
> >>> wrote:
> 
> > ah. good stuff. nice progress.
> >
> >
> > On 16/03/2016 7:50 PM, Steve wrote:
> >
> > Just using the script:
> >
> > freedv_tx 2400A ve9qrp_10s.raw modem.raw
> >
> > Which produces a RAW audio file sampled at 48 kHz and importing that
> >>> into
> > audacity.
> >
> > On Wed, Mar 16, 2016 at 3:46 AM, glen english 
> > wrote:
> >
> >> Hi Steve
> >>
> >> Nice
> >>
> >> is that through a PA- if so, linear or linear in say 3dB
> compression?
> >>
> >>
> >> On 16/03/2016 7:42 PM, Steve wrote:
> >>
> >> Thought I'd upload a spectrum snapshot. You can't really see the
> >> carriers
> >> until you drop the number of samples to about 256, but this shows
> how
> >> wide
> >> it is.
> >>
> >> I noticed that the freedv_tx was outputting +/- 1.0 signals and a
> >>> couple
> >> of clips going on. Maybe need to knock it down to +/- .5 like the
> old
> >> FDM
> >> modes.
> >>
> >> FYI
> >>
> >> Steve
> >>
> >>
> >>
> >>
> >>>
> --
> >> Transform Data into Opportunity.
> >> Accelerate data analysis in your applications with
> >> Intel Data Analytics Acceleration Library.
> >> Click to learn
> >> more.
> http://pubads.g.doubleclick.net/gampad/clk?id=278785231=/4140
> >>
> >>
> >>
> >> ___
> 

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[Adrian Musceac]

Hi David,
You are right, it was measurement error. With the help of Brady's GRC 
flowgraphs, I was able to set up a more reliable test.
The chain was: gnuradio DBPSK modem on laptop -> Yaesu FT60 set on narrow 
deviation -> USRP B200 -> Gqrx
The USRP has fine adjustable gain, between 0 and 70 dB.
I was able to obtain error free copy at 18 dB above noise or 6 dB above 
(scratchy) analog FM. I am using a packet encoder so if 1 bit is lost the whole 
packet is dropped.
The interesting thing is that sometimes the modem would decode at barely 10 dB 
above noise. It was critical to adjust audio levels so that the radio does not 
over deviate.
Also, FM modulation does strange things to my phase, so I had to run a very 
tight FLL band edge loop to keep the constellation stable. I think there is 
still lots of room for improvement there.
Also, I could not make the MSK modem decode after Gqrx demodulation, although 
if I use two analog radios it passes just fine. So I can't provide measurements 
for that modem.
Hope this is useful,

Adrian (YO8RZZ)

On 17 March 2016 18:50:37 GMT, David Rowe  wrote:
>Hi Adrian,
>
>Getting the modem right can be really critical.  It's good that we are 
>discovering this and talking about it in Ham and open source circles, 
>and getting high quality modem code out there.
>
>I learned about modems in the sat-com industry.  As the satellites are 
>expensive, we would try to get our modems to within 0.25dB of theory. 
>Otherwise we were just wasting mega-$.
>
>It still puzzles me why something like DMR has deliberately chosen a 
>modem waveform (with less than Rs Hz spacing tones) that hobbles the 
>system by 6dB.  The power being wasted is like throwing away 3/4 of
>your 
>HT battery.
>
>Suspect of your 16dB loss is a measurement error or perhaps the FM
>modem 
>is not set up right.  I found simulating analog FM and getting 
>performance like the text books to be surprisingly difficult:
>
>   http://www.rowetel.com/blog/?p=3799
>
>Maybe you could first test your FM modem, see if you can get the C/No 
>input versus SNR out curve.
>
>Looking forward, FreeDV 2400A is competitive with SSB for weak signal 
>work today, and I think we can push down another 10dB over time.
>
>Cheers,
>
>David
>
>On 17/03/16 23:11, Adrian Musceac wrote:
>> Hi Brady, David,
>>
>> Thank you very much for sharing the GRC flowgraphs. This will help me
>> a lot setting up a similar test. Regarding the performance, I was
>just
>> surprised to see such a big difference between a modem which runs
>> through analog FM and your new modem. I would have expected something
>> in the range of 6-10 dB, not 16-20 dB. Maybe I need to calibrate my
>> signal again.
>> I enjoyed a lot reading about the experiment on your blog David. It
>> seems like a new revolution for VHF/UHF weak signal work.
>>
>> 73,
>> Adrian (YO8RZZ)
>>
>> On 3/17/16, Brady O'Brien  wrote:
>>> Hey Adrian,
>>>
>>> The gnuradio-companion pipelines I used for the test are attached.
>These
>>> grc pipelines are only meant to get 16-bit 48k samples in and out of
>the
>>> HackRF and rtlsdr for testing. The meat of the FSK is done with the
>C fsk
>>> modem, used in freedv_rx, freedv_tx, fsk_mod, and fsk_demod. We are
>also
>>> running our FSK modem directly from SDR samples instead of through
>FM
>>> radios. We will be running 2400B over legacy FM radios, but don't
>yet have
>>> the same degree of test coverage.
>>>
>>> Thanks,
>>>
>>> Brady O'Brien
>>>
>>> On Wed, Mar 16, 2016 at 3:34 PM, Adrian Musceac 
>wrote:
>>>
 Hi David,

 Is it possible to get our hands on the Gnuradio code? I've been
>trying
 to optimize modems running at 1200 bits/second and the best I could
>do
 was 100% copy at 8 dB above analog FM for DBPSK and 12 dB above for
 GMSK. Your modem seems to be 16-20 dB better than that! If I could
>see
 the Gnuradio graph maybe I could figure out what I'm doing wrong.

 Thanks,
 Adrian

 On 3/16/16, Steve  wrote:
> Ha, I wish it was through a radio!
>
> I'm trying to think what I have laying around here that might make
>a
> good
> transmitter for it.
>
> On Wed, Mar 16, 2016 at 4:02 AM, glen english
>
 wrote:
>
>> ah. good stuff. nice progress.
>>
>>
>> On 16/03/2016 7:50 PM, Steve wrote:
>>
>> Just using the script:
>>
>> freedv_tx 2400A ve9qrp_10s.raw modem.raw
>>
>> Which produces a RAW audio file sampled at 48 kHz and importing
>that
 into
>> audacity.
>>
>> On Wed, Mar 16, 2016 at 3:46 AM, glen english
>
>> wrote:
>>
>>> Hi Steve
>>>
>>> Nice
>>>
>>> is that through a PA- if so, linear or linear in say 3dB
>compression?
>>>
>>>
>>> On 16/03/2016 7:42 PM, Steve wrote:
>>>
>>> Thought I'd upload a spectrum snapshot. You can't really 

Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[Adrian Musceac]

Also, for comparison purposes, here is my 2000 bit/s modem running
through a Yaesu FT60 handheld radio:
https://www.youtube.com/watch?v=bsmGYWxjfjU
The filter in Gqrx is adjusted for wide deviation (5 kHz) but the
signal is only really about 3 kHz wide.

Please note how the signal is 15-16 dB smack on above the noise floor.
If I were to run your modem, it would probably decode even where my
SDR falls over. This is probably because the RTL-SDR has a much lower
noise figure than my USRP, although I will trade that any day for the
12 bit ADC.

73,
Adrian

On 3/16/16, Adrian Musceac  wrote:
> Hi David,
>
> Is it possible to get our hands on the Gnuradio code? I've been trying
> to optimize modems running at 1200 bits/second and the best I could do
> was 100% copy at 8 dB above analog FM for DBPSK and 12 dB above for
> GMSK. Your modem seems to be 16-20 dB better than that! If I could see
> the Gnuradio graph maybe I could figure out what I'm doing wrong.
>
> Thanks,
> Adrian
>
> On 3/16/16, Steve  wrote:
>> Ha, I wish it was through a radio!
>>
>> I'm trying to think what I have laying around here that might make a good
>> transmitter for it.
>>
>> On Wed, Mar 16, 2016 at 4:02 AM, glen english 
>> wrote:
>>
>>> ah. good stuff. nice progress.
>>>
>>>
>>> On 16/03/2016 7:50 PM, Steve wrote:
>>>
>>> Just using the script:
>>>
>>> freedv_tx 2400A ve9qrp_10s.raw modem.raw
>>>
>>> Which produces a RAW audio file sampled at 48 kHz and importing that
>>> into
>>> audacity.
>>>
>>> On Wed, Mar 16, 2016 at 3:46 AM, glen english 
>>> wrote:
>>>
 Hi Steve

 Nice

 is that through a PA- if so, linear or linear in say 3dB compression?


 On 16/03/2016 7:42 PM, Steve wrote:

 Thought I'd upload a spectrum snapshot. You can't really see the
 carriers
 until you drop the number of samples to about 256, but this shows how
 wide
 it is.

 I noticed that the freedv_tx was outputting +/- 1.0 signals and a
 couple
 of clips going on. Maybe need to knock it down to +/- .5 like the old
 FDM
 modes.

 FYI

 Steve



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Re: [Freetel-codec2] new FreeDV 2400A VHF Modem

[Brady O'Brien]

I think in the case of coherent vs non-coherent for 4FSK, the plot of
EbN0(dB) vs BER for ideal coherent and non-coherent says it all. If we find
that we really need that extra dB, It'd be easier to switch to non-coherent
8FSK than write and test coherent 4FSK (and at 8FSK, coherent and
non-coherent are even closer).

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