[hpsdr] Chirp

[Phil Harman]

Hi Mike,

Thanks for the question.   Chirp support is currently work-in-progress.  We 
are building a 2m Chirp beacon (VK6RIO) in Perth to try and crack the Perth 
to South Africa path which has never been done before.

The Perth end will consist of a Penny board synced to a GPS to provide 
frequency lock and 1 PPS for timing. This feeds a modified TenTec 6m radio 
as an exciter then a 100W PA brick.  The antenna system is 4 by 8 element 
yagis.

Tx frequency is 144.950 MHz and the Chirp sweep width is 1kHz over 1 second 
triggered from the 1PPS of the GPS receiver.  The callsign is sent 
periodically by using forward or reverse sweeps to indicate if a 0 or 1 is 
being sent.

The ZS receive end will be a Mercury board plus Metis ( kindly donated by 
TAPR for which we are most grateful) and a GPS to provide frequency lock and 
1 PPS timing.  A 2m down converter will use the 122.88MHz clock from Mercury 
so all oscillators are GPS referenced.

By integrating over a minute we should be able to detect a signal 50dB below 
the noise floor in a 2kHz bandwidth.

In which case the Effective System Power is about 100MW.

Currently the Tx is fully built and tested and I'm about to start building 
the Rx hardware and writing Rx software.

We have tested the Chirp system both across Australia and within Germany and 
we are getting the theoretical system gain.  Andrew, VK3OE, is using a Chirp 
system on 6m (transmitting from a remote site to prevent overload of the 
receiver) in order to do real-time ionospheric  sounding with excellent 
results - you may have read some of his articles.

In Australia we are allowed 100kHz of bandwidth on bands above 12m which 
means we could sweep over 100kHz for an additional 20dB of system gain which 
will make moonbounce an interesting possibility.

I'm also still writing the receiver decoder software as an addition to KISS 
Konsole so will consider releasing that when completed  - or preferably 
offering the task to someone else :)

73 Phil....VK6PH





-----Original Message----- 
From: Mike Seguin
Sent: Wednesday, January 8, 2014 7:29 PM
To: hpsdr at lists.openhpsdr.org
Subject: [hpsdr] Chirp

***** High Performance Software Defined Radio Discussion List *****

Is the software for Chirp available anywhere? This looks like an
extremely interesting mode.

Mike
-- 

73,
Mike, N1JEZ
"A closed mouth gathers no feet"

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