October 21, 2012

First picture from NIWAKA by 5.8GHz

GS says to AMSAT-DL as follows.

> I appreciate your offer of 20m dish.
> The exact frequency is 5840.000 MHz.
> The RF signal is modulated with FSK of 115.2kbps digital picture data.
> Frequency sift is +,- 50kHz, but the spectrum spread over 300kHz.
> As we use a simple FSK, FM detector directly generates the signal for
> serial-port(RS232C) of PC. The discriminator of FM-radio (IF=10.7MHz)
> may be available by removing de-emphasis circuit.
> A jpeg-picture data are sent by packets. Each packet consists
> of 128 byte:
> packet-ID  data-size  picture-data  verify
> (2 byte)   (2 byte)   (122 byte)    (2 byte)
> Namely, the first 4 bytes and the last 2 bytes do not consist the
> photo data. Data-size of all packets except the last is 122(=7A hex).
> A jpeg-picture data starts with "FFD8" and ends with "FFD9".
> The jpeg picture is made by connecting the data part of each packet by
> removing the first 4 byte and the last 2 byte.
> 20 VGA-pictures are sent at a time. Each picture is sent around 4-6 sec.
> There is 8 msec interval between packets. and 5 sec interval between 
> pictures. 
> Please find the block diagrams and circuit schematics in my web-page:
> http://www.fit.ac.jp/~tanaka/

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