Re: [digitalradio] Re: Path Simulations for PAX / HF Packet

[Tony]

Patrick,

> Hello Tony, Glad you did measures for Pax.

My pleasure; thanks for adding the mode to Multipsk!

> My figures are the following: Lowest S/N : - 10 dB for PAX and - 7 dB for
> PAX2. It corresponds to a Gaussian noise without any ionospheric 
> distortion (your
> first case.

Just tested PAX and PAX2 again for the lowest S/N (Gaussian noise only) and 
came up with -11db for PAX and -7db for PAX2. Very close.

> Normally there is a 3 dB difference between these 2 modes as there are
> strictly the same except that Pax2 is twice quicker than Pax.

Understand Patrick. Ionospheric distortion seems to widen the gap between 
the two with PAX coming out ahead by 5db or so. I used the 100% decode 
criteria so that may be the difference.  The PAX2 mode did not print at all 
(regardless of SNR) with the two most disturbing ionospheric simulations.

> Note: Pax and Pax2 modulations are clones of Olivia, let's say very close 
> on
> modulation to Contestia.

No wonder why they work so well!

> For Pax and Packet there is no ARQ memory (contrary to ARQ FAE), so the
> minimum S/N in connected mode would be the same as in Unproto.

Thanks for clarifying that.

> Note: it could be theoritically possible to implement ARQ memory in Pax 
> and
> Packet (which would give a sort of FEC (repetition)coding to these modes),
> but it would need time...

Interesting.

Thanks Patrick. Let me know if I can help with any mode simulations you 
haven't tried yet.

Tony, K2MO

Re: [digitalradio] Re: Path Simulations for PAX / HF Packet

[Patrick Lindecker]

Hello Tony,

Glad you did measures for Pax.

My figures are the following:
Lowest S/N : - 10 dB for PAX and - 7 dB for PAX2

It corresponds to a Gaussian noise without any ionospheric distortion (your 
first case).
In my figures, I accept an error rate of 2 % (2 characters false for 98 
characters good). However with frames it is a bit more difficult to 
appreciate.
Conditions of measure: the sampling speed of the sound card has been 
perfectly determined ("Sampling freq" button) and the sound level (as 
displayed in the "Level" box) is about 20 to 60 % (not critical).

Normally there is a 3 dB difference between these 2 modes as there are 
strictly the same except that Pax2 is twice quicker than Pax.

Note: Pax and Pax2 modulations are clones of Olivia, let's say very close on 
modulation to Contestia.

For Pax and Packet there is no ARQ memory (contrary to ARQ FAE), so the 
minimum S/N in connected mode would be the same as in Unproto.
Note: it could be theoritically possible to implement ARQ memory in Pax and 
Packet (which would give a sort of FEC (repetition)
coding to these modes), but it would need time...

73
Patrick

- Original Message - 
From: "Tony" <[EMAIL PROTECTED]>
To: 
Sent: Sunday, August 24, 2008 11:05 PM
Subject: [digitalradio] Re: Path Simulations for PAX / HF Packet


> Greetings Patrick,
>
>> Hello Tony, TKS for the interesting tests. Did you test PAX or PAX2? with
>> Unproto frames?
>> 73 Patrick
>
> I used PAX2 with Unproto frames during the test. Haven't figured out how 
> to
> test in the 'connect' mode yet. I just finished testing PAX "1" so please
> see below. PAX has a definite advantage in sensitivity over PAX-2 as well 
> as
> the ability to print better when conditions are disturbed.
>
> There's a 3db advantage in sensitivity over PAX-2 when the criteria is 
> based
> on 100% decode. But partial decodes at -6 and -10db vs. 0db and -2db would
> seem to indicated that PAX would do much better than PAX-2 in the ARQ
> connect mode.
>
> Would appreciate your thoughts on this Patrick...
>
> Tony, K2MO
>
> 
>
> PAX: Sensitivity threshold for 100% decode: -11db (no ionospheric
> distortion)
>
> Ionospheric Simulations:
>
> High-Latitude Moderate.Complete decdoe @ -4db SNR. Partial
> decode -10db SNR
> High-Latitude DisturbedNO DECODE
> Mid-latitude Disturbed.Complete decode @ -4db SNR. Partial Decode
> @ -10db SNR
> Low-Latitude Disturbed.Complete decode @ 0db SNR. Partial decode
> @ -6db SNR
>
> PAX2:
>
> Sensitivity threshold for 100% decode: -2db (no ionospheric distortion)
>
> Ionospheric Simulations:
>
> High-Latitude Moderate.Complete decdoe @ +2db SNR. Partial decode
> 0db SNR
> High-Latitude DisturbedNO DECODE
> Mid-latitude Disturbed.Complete decode @ +1db SNR. Partial Decode
> @ -2db SNR
> Low-Latitude Disturbed.NO DECODE
>
>
> HFPAcket (300baud):
>
> Sensitivity threshold for 100% decode: +1db SNR (no ionospheric 
> distortion)
>
> Ionospheric Simulations. NO DECODE*
>
> * Susceptible to slight multi-path timing delays and Doppler Spread; < 1 
> Hz
> / < 1msec
>
>
>
> 
>
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