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OT QRP: Low Power QPSK experiment Advice sought

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Niel Skousen-2

OT QRP: Low Power QPSK experiment Advice sought

Good Evening All,

This is low power, just not strictly QRP operating. I'm looking for input and advice ** off the list **

I'd like to do some experiments with QPSK and GMSK at 450 - 900 MHz, and looking for advice on howto inexpensively do so since I dont have digital modulation signal generator. I'd like to look at some modulation sideband effects at +/- 5x the modulation frequency. Ideally I'm looking at 5Mbps QPSK, but lower bandwidths (~1Mbps) might work for me as similar answers to my question ( interference suppression ).

I have an HP 8921 for Spectrum analysis and a decent scope, but no good way to generate and decode the digital stream.

Any thoughts for on-the-cheap approach would be appreciated (eval kits etc)

Thanks for the Bandwidth

Niel
WA7SSA
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Mel

Re: OT QRP: Low Power QPSK experiment Advice sought

While off topic, hi. Look into the old TV signal simulator generator for the old Satellite band. They had some good test sets for modulating a 30 MHz FM bandwidth. It would be a good place to start. They operated in the 3.7 to 4.2 GHz band, but the test set had the modulation format at 70 MHz. Spread spectrum would be the next area to look. That was all wideband digital. A lot of 900 MHz SS stuff is available with a little effort. A thought.

Mel, K6KBE

On Thursday, March 27, 2014 4:57 PM, Niel Skousen <[hidden email]> wrote:

Good Evening All,

This is low power, just not strictly QRP operating. I'm looking for input and advice ** off the list **

I'd like to do some experiments with QPSK and GMSK at 450 - 900 MHz, and looking for advice on howto inexpensively do so since I dont have digital modulation signal generator. I'd like to look at some modulation sideband effects at +/- 5x the modulation frequency. Ideally I'm looking at 5Mbps QPSK, but lower bandwidths (~1Mbps) might work for me as similar answers to my question ( interference suppression ).

I have an HP 8921 for Spectrum analysis and a decent scope, but no good way to generate and decode the digital stream.

Any thoughts for on-the-cheap approach would be appreciated (eval kits etc)

Thanks for the Bandwidth

Niel
WA7SSA
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Don Wilhelm-4

Re: OT QRP: Low Power QPSK experiment Advice sought

In reply to this post by Niel Skousen-2

Neil,

If you are going to operate digital modes, you have a perfectly good way
to generate the digital stream.
It is the computer soundcard and the application that you will be using.
The computer soundcard is good for generating anything in the audio
range. There are several software applications that will produce
several types of audio waveforms. A web search will reveal several of them.
But for your purposes, I would think that the software application that
you intend to use to generate the digital signal would be the best thing
to use.

73,
Don W3FPR

On 3/27/2014 7:41 PM, Niel Skousen wrote:

> Good Evening All,
>
> This is low power, just not strictly QRP operating. I'm looking for input and advice ** off the list **
>
> I'd like to do some experiments with QPSK and GMSK at 450 - 900 MHz, and looking for advice on howto inexpensively do so since I dont have digital modulation signal generator. I'd like to look at some modulation sideband effects at +/- 5x the modulation frequency. Ideally I'm looking at 5Mbps QPSK, but lower bandwidths (~1Mbps) might work for me as similar answers to my question ( interference suppression ).
>
> I have an HP 8921 for Spectrum analysis and a decent scope, but no good way to generate and decode the digital stream.
>
> Any thoughts for on-the-cheap approach would be appreciated (eval kits etc)
>
>

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Lynn W. Taylor, WB6UUT

Re: OT QRP: Low Power QPSK experiment Advice sought

He's talking about 1 megabit to 5 megabit data rates.

Not going to do more than a few kilobits with a sound card.

-- Lynn

On 3/27/2014 6:17 PM, Don Wilhelm wrote:

> Neil,
>
> If you are going to operate digital modes, you have a perfectly good
> way to generate the digital stream.
> It is the computer soundcard and the application that you will be using.
> The computer soundcard is good for generating anything in the audio
> range. There are several software applications that will produce
> several types of audio waveforms. A web search will reveal several of
> them.
> But for your purposes, I would think that the software application
> that you intend to use to generate the digital signal would be the
> best thing to use.
>
> 73,
> Don W3FPR
>
> On 3/27/2014 7:41 PM, Niel Skousen wrote:
>> Good Evening All,
>>
>> This is low power, just not strictly QRP operating. I'm looking for
>> input and advice ** off the list **
>>
>> I'd like to do some experiments with QPSK and GMSK at 450 - 900 MHz,
>> and looking for advice on howto inexpensively do so since I dont
>> have digital modulation signal generator. I'd like to look at some
>> modulation sideband effects at +/- 5x the modulation frequency.
>> Ideally I'm looking at 5Mbps QPSK, but lower bandwidths (~1Mbps)
>> might work for me as similar answers to my question ( interference
>> suppression ).
>>
>> I have an HP 8921 for Spectrum analysis and a decent scope, but no
>> good way to generate and decode the digital stream.
>>
>> Any thoughts for on-the-cheap approach would be appreciated (eval
>> kits etc)
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Don Wilhelm-4

Re: OT QRP: Low Power QPSK experiment Advice sought

Lynn,

Then he is going to drive it with something other than a soundcard in
his 'real life' situation.
I am suggesting that whatever he will be driving it with is a valid
signal generator.
Of course, if he wants to test well beyond the limits of whatever will
be driving it, that is a different matter and may require quite
specialized equipment. I do not know enough from the original post to
comment any further.

73,
Don W3FPR

On 3/27/2014 9:27 PM, Lynn W. Taylor, WB6UUT wrote:
> He's talking about 1 megabit to 5 megabit data rates.
>
> Not going to do more than a few kilobits with a sound card.
>

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DL6OAP

Re: OT QRP: Low Power QPSK experiment Advice sought

I am no expert in the field, but maybe the device named "HackRF" is what you are looking for.
It is a low power SDR transceiver with an interface to GNU radio, and, with a 20 Ms/s sampling (if I remember correctly - don't have the data sheet here) rate, the baseband should be broad enough for generating a QPSK signal in the Mbit/s range...

Greetings

Ralf, DL6OAP
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