This weekend’s VOA Radiogram
will include some experiments.
Simultaneous text and
image. One experiment will be the
simultaneous transmission of text and an image. The text of the VOA News story
about men overeating will be transmitted in MFSK32 at the usual center audio
frequency of 1500 Hz. The MFSK32 image accompanying this story will be
transmitted simultaneously at a center audio frequency of 2200 Hz. You will need
two instances of Fldigi; that is, start Fldigi once, then start it again. If you
cannot run two instances of Fldigi (some operating systems don’t allow it), you
can decode the image at 2200 Hz later from a recording. (You could also run
Fldigi and MultiPSK simultaneously.)
At 15 seconds after the text
begins, a tuning signal will help you find the exact center frequency near 2200
Hz. The image itself will start 20 seconds after the tone begins.
I had to reduce the audio level
of both the text and image by 3 dB so that the combined audio of the text and
image would not overload the transmitter and your receiver. This simultaneous
transmission will be followed by the image only, at 1500 Hz, and at full audio
QR codes. The broadcast will include two QR codes. They look
like this …
You scan the QR code, usually
with your mobile device, to obtain information.
The first QR code will follow
the VOA News Story about Middle East hackers. It will provide the link to the
full text of the story. The second QR code will be at the end of the show, with
the VOA Radiogram transmission schedule.
I don’t know much about QR
codes, so your advice would be appreciated. Are the transmitted QR codes too
big? Unnecessarily big? How small can I make them? (The smaller they are, the
less time required to transmit them.)
Here is the lineup for VOA
Radiogram, program 138, 21-22November
2015, all in MFSK32 except where noted:
2:44 Earth-like exoplanet
may not be habitable*
7:29 New tool to search for
11:13 Analysts warn of
Middle East hackers*
20:43 Men overeat to show
off to women (simultaneous image)*
VOA Radiogram transmission
schedule (all days and times
UTC): Sat 0930-1000 5865 kHz Sat 1600-1630 17580 kHz Sun 0230-0300 5745
kHz Sun 1930-2000 15670 kHz All via the Edward R. Murrow transmitting
station in North Carolina.
KBC will transmit a minute of MFSK32
Sunday at 0130 UTC (Saturday 8:30 pm EST) on 7395 kHz, via Germany. This is part
of the KBC broadcast to North America Saturday 2300 UTC to Sunday 0200 UTC on
7395 kHz. Reception reports for KBC reception and decoding to Eric: firstname.lastname@example.org .
Thanks for your reception
reports. Today I hope to answer the last of the reports from program 130, then
I’ll put together the MFSK image gallery from program 131.
I hope you can tune in and
write in. Have fun with the experiments.