Date   

ULTRA CHEAP DONGLE OFF AIR MONITOR

Graham
 

ULTRA CHEAP DONGLE OFF AIR MONITOR

No need to tie up a radio now to monitor off air , with the latest
versions of the `Ultra cheap dongle' project , the R820T dongle offers
good sensitivity from 24 MHz to pas 1000 MHz and is cheaper than the
E4000 based version (£15 in uk), which fails round 60 MHz and is no longer
in production.

Slightly out side its published limits the latest R820T based USB-2
dongle provides direct access to 12 , 10 , 6 , 4 , 2 Mtrs and 70 23 CM

The addition of a connection to `Pin 1' of the A/D chip, via a 0.1 uF
, allows `Direct Sample' mode from round 24 MHz down to well past 136
KHz , in this mode , the addition of a suitable ATU improves performance

The SDR sharp software has features that compliment `data' use , simple
set up , good spectrum and waterfall and drag-configurable bandwidth , up
to 20 KHz in SSB
Click qrg selection , there are other sdr packages , perhaps more suited
to ssb/cw use , but with the up-date facility , sdr-sharp offers a good
`fit and forget' package

Dongle mode selection is via the `controller' application , available by
clicking the `configure' button , the SDR app must be `stopped' first ,
giving Quadrature sampling , for normal use , or Direct sampling (I
Branch) for modified LF>HF

Once the mode is selected , then the appropriate frequency correction
(ppm) can be inputted , this slews the recovered frequency from the
Dongle for netting purposes , further correction may be applied in the
main software , with the `shift ` function

Access to AGC and Gain control is also part of this `pop up' menu


Results

Using a co linera , comparable results to the ft897 are obtained on
VHF

70/50 MHz , gives better performance than my 144/70 transvertor , giving
equal signals from gb3bux on 50 MHz and 70 MHz at 50 miles range

Quad sample mode, 24/28 MHz , using tuner and 14 MHz H Ae , excellent
results

HF , direct sample , using 40 vertical and tuner , compatible to the
ft897 but lower `noise' due to the removal of the mixer chip R820T from
the signal path , noting that minimum decode levels are based on s/n ,
lowering the system noise ,

NB , this is a `Ultra-Cheap' 8 Bit solution , large carriers will cause
problems , there are the odd `spur' but for £6 / £10 , it provides a
effective off air monitor !.


Audio from the sdr software may be shared by selecting the common
windows sound driver , or by one of the `virtual' audio link software's


The latest version of the SDRsharp software may be found :-

http://sdrsharp.com/index.php/downloads

This software has a dos based installation scrip that recovers the
latest versions of the file set from the web and unpacks them , making
updates nice and simple , re-run and reload driver , job done , even the icon
links remain !

http://sdrsharp.com/downloads/sdr-install.zip

There are various help files etc , but once un-packed , all that is needed
is to use the windows based drive installation tool zadig.exe , to load
the driver and that's it
[noting the USB port forms part of the address , so the dongle needs to
be in the port interned for use]

More than one device may be installed in the same machine and addressed
via the software control and device selection panels, one standard and
one modified , gives 'dc to 1500 MHz coverage for very little outlay and may
addressed in the same pc by two sessions of a sdr software

73 -All

G..


Re: Best Digital Mode Software ?

José Angel Amador
 


Replies may vary, it depends on what you want.

Check for Olivia, JT65 and JT9, not necessarily in that order neither being exhaustive.

73,

Jose, CO2JA

El 30/04/2013 6:35, sanil73 escribió:
Hello,
Kindly suggest me the best digital mode software sensitive to weak signals?
Anil  VU2TRI



Net14 April Report

G0JXN Jim
 

Hi Guys

The Net14 April report has been uploaded to www.net14.org.uk (Last Month's Report).

Some interesting maps plotting Damir's, 9A3ADE, voyage from the Red Sea towards Japan. Also Carl, K1CKK, has provided a map showing his transatlantic 30m APRS DX.

73

Jim, G0JXN/MB7UXN


Re: Best Digital Mode Software ?

Craig Wallen
 

Check out some of my test of different software's it is amazing how much difference there is in-between software's. http://ac4m.us/psk_software_test.html
I did the test with BPSK31, CW, JT65 and RTTY, I am not sure what causes some of the differences in BPSK maybe filtering or the FFT calculations, some do better than others for multipath and some do better with sensitivity.
These test were done in a controlled environment, just not a opinion of on the air reception.

I did not test all software's out there but some of the more major ones.

--- In digitalradio@yahoogroups.com, sanil73 <sanil73@...> wrote:

Hello,
Kindly suggest me the best digital mode software sensitive to weak signals?
Anil VU2TRI


Re: MT63 vs. RTTY Simulation For Graham

Tony
 

On 4/30/2013 7:18 PM, graham787 wrote:
 

There will be a factor , due to baud rate / wpm , if the rtty is 60 wpm , what speed was mt63 , that needs to be factored in

Graham:

The speed is about 50 wpm (MT63-500) so it's not quite the apples-to-apples comparison. I believe the two are close enough for demonstration purposes i.e, showing the benefit of FEC on fading channels.

If you make up a jamming tape , say a rtty contest on 14 MHz :) or CW contest on 7 MHz and run that in parallel with the audio feed, via a mixer ? , that would show the advantage of the dsss coding in mt63 , then run olivia at the same power/data rate and that wold show the next level of improvement with mfsk dsss and Walsh coding

Yes, that would certainly be a challenging for any mode. I've done something similar by superimposing tones on the channel to simulate QRM. I found that MT63 tends to print well under those circumstances and my guess is that other modes with aggressive FEC and similar bandwidth would do OK as well.  

Would be interesting to see how Opera decodes in that environment !

It's been a while since I've tested ROS modes with the path simulator. I gave up when I couldn't get ROS to sync correctly; the sync tones needed a much stronger signal to start the process of decoding. I'm not sure if any changes were made to the modem since then?

Thanks Graham...   

Tony -K2MO

, the apparent low carrier level in mt63 is not a 'problem' as its the 'energy' needed to transfer the data that is the yard stick, the decode process 'recovers' the distributed signal,as long as the test tone level is the same as the rtty , that should be correct ?

If you make up a jamming tape , say a rtty contest on 14 MHz :) or CW contest on 7 MHz and run that in parallel with the audio feed, via a mixer ? , that would show the advantage of the dsss coding in mt63 , then run olivia at the same power/data rate and that wold show the next level of improvement with mfsk dsss and Walsh coding

Would be interesting to see how Opera decodes in that environment !

73-Graham

--- In digitalradio@..., Tony wrote:
>
> On 4/29/2013 6:56 PM, graham787 wrote:
>
> peak/mean power is low, but that's part of the mode dynamics , energy
> spread over the band and re-combined during de-code to give a high
> resistance to selective fade / qrm , s/n are not particularly low, worse
> than rtty ?
>
>
> Graham:
>
> True, and tests show that MT63 does do quite well with fading which is
> obviously what it was developed for. The minimum s/n is somewhat lower
> (MT63-500) compared to RTTY.
>
> Here's a short video that shows a side-by-side comparison with RTTY.
>
> http://www.youtube.com/watch?v=MWf83WKaudw
>
> I believe the path simulator takes the peak-to-average ratio into
> account; at least that's what I'm lead to believe from the audio file
> analysis of each mode.
>
> Tony -K2MO
>



Re: Power on digital modes

Larry Mundinger
 

On 04/30/2013 06:49 PM, Adam Jacobs wrote:



Could you explain a bit more about how PSK's average power is 41% of
the peak? If you have a link that would be great.
I use Fldigi which has a "Tune" button which puts out a single tone. I
would set my output power to say 25W and then go to idles and the power
shown on my tuner would drop considerably. Why?

If you look at the PSK signal coming out of a sound card it is amplitude
modulated so that the phase transitions occur when the amplitude is
zero. This reduces bandwidth. When sending idles the phase changes
every bit period. The modulating function is a Cosine function. Fldigi
allows you to look at the waveform instead of the waterfall.

If we set the peak amplitude at 1 volt and evaluate the integral of Cos
(x) from 0 to PI/2 radians and divide by PI/2 we get the average voltage
of .6366 volts.

A non modulated signal of the same (peak) amplitude would have an
average voltage of 1 volt.

Squaring .6366 gives .4053 for the average power.

Yes, I spent quite a bit of time with the dummy load and my MFJ
SWR/Power meter verifying that when switching from a single tone to PSK
idles the average power drops to 41%. If it doesn't then the rig is
being over-driven and putting out a wide signal. Increasing the drive
to the point where ALC action occurs just means that the extra power is
going into splatter and not useful signal.

The 41% figure only holds for idles. During text communication there
are consecutive bits with the same phase so the signal does not go to
zero amplitude between bits and the average power bounces up higher.

I have been told that when reporting power one should report peak power
rather than average power but I have not seen it spelled out in any
contest rules for QRP status. Perhaps it should be.

Larry, KG4Q


Re: MT63 vs. RTTY Simulation For Graham

Graham
 

Ok Tony

There will be a factor , due to baud rate / wpm , if the rtty is 60 wpm , what speed was mt63 , that needs to be factored in , the apparent low carrier level in mt63 is not a 'problem' as its the 'energy' needed to transfer the data that is the yard stick, the decode process 'recovers' the distributed signal,as long as the test tone level is the same as the rtty , that should be correct ?

If you make up a jamming tape , say a rtty contest on 14 MHz :) or CW contest on 7 MHz and run that in parallel with the audio feed, via a mixer ? , that would show the advantage of the dsss coding in mt63 , then run olivia at the same power/data rate and that wold show the next level of improvement with mfsk dsss and Walsh coding

Would be interesting to see how Opera decodes in that environment !

73-Graham

--- In digitalradio@yahoogroups.com, Tony <DXDX@...> wrote:

On 4/29/2013 6:56 PM, graham787 wrote:

peak/mean power is low, but that's part of the mode dynamics , energy
spread over the band and re-combined during de-code to give a high
resistance to selective fade / qrm , s/n are not particularly low, worse
than rtty ?


Graham:

True, and tests show that MT63 does do quite well with fading which is
obviously what it was developed for. The minimum s/n is somewhat lower
(MT63-500) compared to RTTY.

Here's a short video that shows a side-by-side comparison with RTTY.

http://www.youtube.com/watch?v=MWf83WKaudw

I believe the path simulator takes the peak-to-average ratio into
account; at least that's what I'm lead to believe from the audio file
analysis of each mode.

Tony -K2MO


Re: Power on digital modes

Adam Jacobs <jacobs.adam@...>
 

The problem with the "minimum power to accomplish the desired communication" thing is that folks will QRO pretty far before they give up and throttle back. If you're not begin heard on JT65 at 30w, odds are you won't be heard at 100w... but that doesn't stop folks from giving it a shot or 12. :)

Could you explain a bit more about how PSK's average power is 41% of the peak? If you have a link that would be great.

-73 Adam W7QI

On 4/30/2013 3:35 PM, Larry Mundinger wrote:
 

On 04/30/2013 05:31 PM, W. J. Karle wrote:
>
>
> It seems to me that users of digital modes gradually are increasing
> their radiated powers. Whereas we once prided ourselves saying that
> our rigs were running 30 watts or less, now I am seeing more and more
> hams saying that they are running 50 and 75 watts.

I have seen some of this as well. I wonder if there is a question on
the test about duty cycle? Digital modes are 100% duty cycle and
transceivers aren't rated for that. The maximum power specification for
AM should be observed rather than that for SSB and CW. You can push it
some on PSK because the average power is 41% of the peak power but not
on the FSK modes. A friend of mine recently admitted that he melted his
linear's power transformer during a RTTY contest so cheer up - the
problem can be self limiting.

Actually, we are required to use the minimum power to accomplish the
desired communication.

Larry, KG4Q



Re: Power on digital modes

Larry Mundinger
 

On 04/30/2013 05:31 PM, W. J. Karle wrote:


It seems to me that users of digital modes gradually are increasing
their radiated powers. Whereas we once prided ourselves saying that
our rigs were running 30 watts or less, now I am seeing more and more
hams saying that they are running 50 and 75 watts.
I have seen some of this as well. I wonder if there is a question on
the test about duty cycle? Digital modes are 100% duty cycle and
transceivers aren't rated for that. The maximum power specification for
AM should be observed rather than that for SSB and CW. You can push it
some on PSK because the average power is 41% of the peak power but not
on the FSK modes. A friend of mine recently admitted that he melted his
linear's power transformer during a RTTY contest so cheer up - the
problem can be self limiting.

Actually, we are required to use the minimum power to accomplish the
desired communication.

Larry, KG4Q


MT63 vs. RTTY Simulation For Graham

Tony
 

On 4/29/2013 6:56 PM, graham787 wrote:

peak/mean power is low, but that's part of the mode dynamics , energy spread over the band and re-combined during de-code to give a high resistance to selective fade / qrm , s/n are not particularly low, worse than rtty ?


Graham:

True, and tests show that MT63 does do quite well with fading which is obviously what it was developed for. The minimum s/n is somewhat lower (MT63-500) compared to RTTY.

Here's a short video that shows a side-by-side comparison with RTTY.

http://www.youtube.com/watch?v=MWf83WKaudw

I believe the path simulator takes the peak-to-average ratio into account; at least that's what I'm lead to believe from the audio file analysis of each mode.

Tony -K2MO


Re: Grumffff

W. J. Karle <ve4kz@...>
 

"Us vs Them" is a perennial discussion point in ham radio as elsewhere.  I would like to comment about 'Us'.

It seems to me that users of digital modes gradually are increasing their radiated powers.  Whereas we once prided ourselves saying that our rigs were running 30 watts or less, now I am seeing more and more hams saying that they are running 50 and 75 watts.  The appearance of their signals, the signal strength, and the signal-to-noise ratio suggests that many indeed are radiating more power, unless my system gradually has become more sensitive to signals while noise sources have declined, neither of which are likely.

Lest one can mitigate the effect of these strong signals by using narrow receive bandwidths, disabling the AGC, and manually adjusting RF gain, then weaker signal copy becomes problematic if not impossible.

Mitigation skills are well worth developing.  Yet, it is my opinion that we all need to more or less equalize our radiated powers and, if possible, reduce radiation.   Our digimodes, after all, do provide good throughput even at low SNRs.

Thanks for considering.

73,

Bill





Re: Grumffff

Adam Jacobs <jacobs.adam@...>
 

... and bad neighbor contesters aren't limited to RTTY. The worst offenders when it comes to working all over the top of the JT65 & PSK31 sections of the band are the CW contesters (in my experience). I've definitely had to carefully massage the passband edges in my SDR receiver to exclude the QRO CW signals and decode the JT65.

-73 Adam W7QI

On 4/30/2013 1:25 PM, Jerry wrote:
 

That is true.. Some are very good ops… I need to clarify… It is the BAD Ops that need to go away…

 

You sound top notch…

 

73 jk

 

From: digitalradio@... [mailto:digitalradio@...] On Behalf Of Thomas F Giella W4HM
Sent: Monday, April 29, 2013 9:14 AM
To: digitalradio @ Yahoo
Subject: [digitalradio] Re: Grumffff

 

 

Some RTTY contesters do care. I operated in the RTTY contest over the
weekend and I was always careful not to QRM any other digital mode.

That included the weak signal modes JT65A and JT9 between 14079 kc and
21076-21079 kc. I also avoided the international radio wave propagation
beacon network on 14100 kc, etc.

73 & GUD DX,
Thomas F. Giella W4HM
Lakeland, FL, USA
w4hm@...

BARTG #8531
PODXS 070 #349
FELD HELD #141
30MDG # 691
DMC #1243
WARC-CC #20

W4HM Amateur Radio & SWL Autobiography: http://www.w4hm.org
W4HM Daily MF/HF/6M Radio Wave Propagation Forecast:
http://www.solarcycle24.org
Lakeland, FL Daily Climatological Weather Data Archive:
http://www.wcflunatall.com/nz4o22.htm



Re: Grumffff

Jerry <n9lya@...>
 

That is true.. Some are very good ops… I need to clarify… It is the BAD Ops that need to go away…

 

You sound top notch…

 

73 jk

 

From: digitalradio@... [mailto:digitalradio@...] On Behalf Of Thomas F Giella W4HM
Sent: Monday, April 29, 2013 9:14 AM
To: digitalradio @ Yahoo
Subject: [digitalradio] Re: Grumffff

 

 

Some RTTY contesters do care. I operated in the RTTY contest over the
weekend and I was always careful not to QRM any other digital mode.

That included the weak signal modes JT65A and JT9 between 14079 kc and
21076-21079 kc. I also avoided the international radio wave propagation
beacon network on 14100 kc, etc.

73 & GUD DX,
Thomas F. Giella W4HM
Lakeland, FL, USA
w4hm@...

BARTG #8531
PODXS 070 #349
FELD HELD #141
30MDG # 691
DMC #1243
WARC-CC #20

W4HM Amateur Radio & SWL Autobiography: http://www.w4hm.org
W4HM Daily MF/HF/6M Radio Wave Propagation Forecast:
http://www.solarcycle24.org
Lakeland, FL Daily Climatological Weather Data Archive:
http://www.wcflunatall.com/nz4o22.htm


QRE: Re: Best Digital Mode Software ?

Dave AA6YQ
 

David G3YYD’s new 2-Tone RTTY decoder does very well with weak signals, selective fading, and nearby QRM. WinWarbler includes both the MMTTY engine and 2-Tone, enabling simultaneous decoding of a RTTY signal by both decoders.

 

While many applications do use Moe AE4JY’s PSKCORE engine, they differ in the extent to which they exploit PSKCORE’s ability to decode up to 50 signals simultaneously. Here’ what WinWarbler provides:

 

<http://www.dxlabsuite.com/winwarbler/Heard.jpg>

 

Double-click an entry in the table, and make your call…

 

      73,

 

           Dave, AA6YQ

 

 

 

From: digitalradio@... [mailto:digitalradio@...] On Behalf Of Andrew O'Brien
Sent: Tuesday, April 30, 2013 7:48 AM
To: digitalradio
Subject: Re: [digitalradio] Re: Best Digital Mode Software ?

 

 

For PSK31 you will find that most use the same "core", so the reception capabilities will be about the same.  For RTTY , many use the same "engine" (MMTTY) , so there will also be some common aspects in terms of decoding.  A few RTTY applications doe have some different techniques, such as the latest release of FLdigi.  For weak signals, many of the modes in MUltipsk will do very wll, especially ALE400. For super weak signals, spefici modes may be the issue, Multipsk includes JT65A.  There are also stand alone modes like WSPR, Opera, and JT9. I find that I use Winwarbler for RTTY and PSK31, Mulspsk for many modes and Fldigi.

 

Andy K3UK

 

On Tue, Apr 30, 2013 at 7:22 AM, skip.kline <skip.kline@...> wrote:

 

Hi Anil. There are many good programs. I suggest you try fldigi; it covers all modes except JT-65 and is quite sensitive. Moreover, it's easy to use and free!

73 de Skip



--- In digitalradio@..., sanil73 <sanil73@...> wrote:
>
> Hello,
> Kindly suggest me the best digital mode software sensitive to weak signals?
> Anil VU2TRI
>

 


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Re: Best Digital Mode Software ?

Andrew OBrien
 

For PSK31 you will find that most use the same "core", so the reception capabilities will be about the same.  For RTTY , many use the same "engine" (MMTTY) , so there will also be some common aspects in terms of decoding.  A few RTTY applications doe have some different techniques, such as the latest release of FLdigi.  For weak signals, many of the modes in MUltipsk will do very wll, especially ALE400. For super weak signals, spefici modes may be the issue, Multipsk includes JT65A.  There are also stand alone modes like WSPR, Opera, and JT9. I find that I use Winwarbler for RTTY and PSK31, Mulspsk for many modes and Fldigi.

Andy K3UK


On Tue, Apr 30, 2013 at 7:22 AM, skip.kline <skip.kline@...> wrote:
 

Hi Anil. There are many good programs. I suggest you try fldigi; it covers all modes except JT-65 and is quite sensitive. Moreover, it's easy to use and free!

73 de Skip



--- In digitalradio@..., sanil73 wrote:
>
> Hello,
> Kindly suggest me the best digital mode software sensitive to weak signals?
> Anil VU2TRI
>



Re: Best Digital Mode Software ?

skip.kline
 

Hi Anil. There are many good programs. I suggest you try fldigi; it covers all modes except JT-65 and is quite sensitive. Moreover, it's easy to use and free!

73 de Skip

--- In digitalradio@yahoogroups.com, sanil73 <sanil73@...> wrote:

Hello,
Kindly suggest me the best digital mode software sensitive to weak signals?
Anil VU2TRI


Best Digital Mode Software ?

sanil73 <sanil73@...>
 

Hello,
Kindly suggest me the best digital mode software sensitive to weak signals?
Anil  VU2TRI


Re: DM780 Typing Buffer Delay Issue + MT63 Manual Tuning?

Tony
 

Karle:

Thanks for the information. Wonder if it's worth reverting back to the older versions.

Tony -K2MO


On 4/28/2013 11:27 PM, W. J. Karle wrote:
 
I have not seen a _periodic_ delay or pause.  What I see is one or the other of two odd outputs when I have typed four or more_lines_ ahead and then backspace perhaps half of a line.  One odd output is that the buffered text is not modulating the carriers in, for example, BPSK.  The other odd output is that a single character is output and then a line feed is transmitted, then another character and line feed, and so on.

The cure for me is to Quit DM780, restart, re-enter the other person's call, and continue.

I am using version 5.24.0.38.  My earlier version (5.11 ??) did not have this problem.

73,

Bill
 





Re: DM780 Typing Buffer Delay Issue + MT63 Manual Tuning?

Graham
 

Its a old mode now , from 1997 , these levels are listed in multipsk help files , the peak/mean power is low, but that's part of the mode dynamics , energy spread over the band and re-combined during de-code to give a high resistance to selective fade / qrm , s/n are not particularly low, worse than rtty ?

G,,

Pmean/Ppeak: 0.1

Lowest S/N : -8 dB for 5 bauds, - 5 dB for 10 bauds and -2 dB for 20 bauds (without sampling frequency offset).

--- In digitalradio@yahoogroups.com, Tony <DXDX@...> wrote:

On 4/29/2013 3:36 PM, graham787 wrote:

I did try it on 500K but with very limited results, nice copy locally
, but after that not too good ,
The forward error correction does seem to handle long fades quite well
so I think it's a worth experimenting with. I guess the drawback is the
high peak to average ratio and the long latency.

drm-780 that gives the rx off-set in HZ ? but sends, fixed mid-band ?
fldigi may be more practical then ?
I find it more convenient to set the tone frequency Graham. One reason
is that I have my Flex radio filters centered on 1500Hz. All the DM780
modes are fine except for MT63 ; )

Tony


Re: RTTY galore

Ralph Mowery
 

Even at 170 hz shift the abiltity to copy on only one tone is often useful on the low bands.  I have watched a scope used for tuning many hours in the past on the old mechanical systems.  The mark tone will fade out and then come back and then the space tone will do the same thing under some band conditions.   Having one of the old ST-6 demodulators often provided good copy when the old pix were being transmitted.  The ST-4 would not copy on only one tone and did not do as well.
 
It is not that tones get clobbered  under contests, but the selective fading where that ability comes in handy.
I guess that under contest conditions it may be helpful if you can crank in enough selectivity so only one tone is actually being used.  I don't know as I do not do the contests.
 

From: "jhhaynes@..."
To: digitalradio@...
Sent: Monday, April 29, 2013 5:28 PM
Subject: [digitalradio] Re: RTTY galore

W1HKJ recently added to fldigi the ability to copy on mark-only or
space-only.  This feature was already in cocoaModem.  A number of
the old hardware demodulators had this feature, intended to allow you
to get some copy even if one of the two tones is clobbered by QRM.

It remains to be seen whether the feature is useful.  An article
by the late Irv Hoff suggested that interference of that kind was
a lot more prevalent with 850 Hz shift.  So reports are solicited
from those who participate in cutthroat RTTY contesting as to
whether the feature is useful.

Jim W6JVE



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