[A-DX] VOA Radiogram, 25-26 February: Three flavors of MFSK

[Reinhard Weiß]

Hallo Roger,

ich glaube das 10 Sekunden Tuning-Signal ist eher für diejenigen, die 
den Decoder manuell auf die richtige Betriebsart umstellen müssen, oder 
weil die automatische Erkennung nicht zugeschlagen hat (wie bei mir 
gerade auf 15670).

Abgesehen davon verstehe ich nicht, was MFSK16/32/64 mit den 
Empfangsbedingungen zu tun haben soll, wenn sich die damit verbundene 
Bandbreite 1:1 auf den Datendurchsatz/WPM durchschlägt. Damit bleibt das 
SNR ja konstant, oder?

Viele Grüße
Reinhard

Am 26.02.2017 um 19:02 schrieb Roger:
> Am 25.02.2017 um 15:06 schrieb Mike Terry  
> [dxld]:
>> VOA Radiogram is a Voice of America program experimenting with 
>> digital text and images via shortwave broadcasting. It is produced 
>> and presented by Dr. Kim Andrew Elliott.
>> With reception conditions apparently improving, we will take a chance 
>> with MFSK64 (240 wpm) for one of our news stories this weekend.
>>
> When using the faster MFSK64-mode  one should also use the 
> possibilities of FLMSG. This allows you to check the CRC of the 
> received (formatted) texts.
>
>
>
>> But if reception conditions are poor, we will also transmit one story 
>> in MFSK16 (58 wpm).  Tuning for MFSK16 needs to be precise, so if the 
>> RSID does not work, I precede it with a 10-second tuning signal.
>
> A precise frequency tuning is only important for LSB or USB,  if you 
> use "own" demodulation carriers
> If one demodulates in AM, or in S-AM, the relative distance of the 
> useful signal / carrier does not change. So you can always work with a 
> FLDIGI fixed to 1500 Hz.
>
> Even a frequency drift of receiver or transmitter of 1 kHz would be no 
> problem  -  in AM.
>
>
>>
>> So this will be a weekend to compare MFSK16, 32, and 64, including 
>> one image transmitted in both MFSK64 and 32, and another image 
>> transmitted in both MFSK16 and 32
>
>
> Images in MFSK-16 have the lowest resolution, despite the same 
> transmission time.
> In addition, they are particularly susceptible to interference 
> patterns from the audio intermodulation products of the aged station 
> in Greenville.
>
> Perhaps the HAARP transmitters could also broadcast the VOA-radiogram, 
> while they heat up the Ionosphere .... ;-)
>
>
> <http://www.rhci-online.net/radiogram/VoA_Radiogram_2017-02-25.htm#HAARP>
>
> http://www.rhci-online.net/radiogram/VoA_Radiogram_2017-02-25.htm#HAARP
>
>
> roger
>
>
>
>
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-- 
QTH südlich von München