[time-nuts] cheap DVB-T USB dongles and HF digital mode reception

[Tofurk Ei]

>> Further maybe even obtain better performance. But thats far from my
>> concern right now. I simply want to get the systems back online to watch
>> propagation behaviors as I have for years.
>
(DVB-T dongles could excel at that.. automated digitally tuned reception..)

> I don't see how. The time transmitted will have the same propagation
> issues as the 60 kHz, so will be subject to diurnal variations plus
> ionospheric randomness.
>
>> Maybe in the future there will be a $7 chip set that magically does whats
>> been written by nist/John Lowe. Or like someone suggested we get the dtv
>> tuner coupon. :-) Not likely.
>

Did you mean the Realtek DVB-T dongles? well.. its hard to beat them for
the money.. But they aren't a complete solution unless they are paired with
a computer..

However, recently Leif, SM5BSZ, the author of Linrad, discovered a way to
fully turn off the AGC.. that is a really great new development which makes
them much more useful for measurement.

http://www.nitehawk.com/sm5bsz/linuxdsp/hware/rtlsdr/rtlsdr.htm

With an upconverter (like the one below)
http://www.george-smart.co.uk/wiki/FunCube_Upconverter
a nice digital receiver for 3 - 30 MHz (or the lower frequency bands) can
be built for very little money.. They already handle VHF-UHF...

As USB devices they need a USB host. Also application software like
gnuradio or even linrad do require a decent powered CPU. But they do work
okay with the $30 raspberrypi (700 MHz ARM)

With the rtlsdr driver one can also output directly to a FIFO or TCP_IP,
but something would have to process that to make use of that data..

Anyway, seeing the bit about the $7 coupon and suspecting that was what was
being mentioned, I thought I should pass this info on..

They are what they are.. cheap devices.. kind of like those Sure GPS
modules..

But nonetheless they are tons of fun and very useful in applications where
all is needed is SOME way of receiving some signal cheaply, as long as you
don't expect them to do much more than that..

 Then, having shed any lofty expectations, you will be pleasantly surprised
at what they can do.

-Tofurk



> Could well be just an EPROM, but you need all the other stuff to support
> it...  antenna, cables, power supply. A $7 will not be the end of it.
>
> YMMV,
>
> -John
>
> ================
>
>> But it does truly seem possible to succeed on this. Maybe its our skills
>> that are insufficient to pull this off. But I haven't given up at all.
>> Just delayed with family...
>> Can't wait to heat the soldering iron up late next week.
>>