[time-nuts] LORAN-C and the SDR-IQ

Brooke Clarke brooke at pacific.net
Sat Jan 20 15:07:33 EST 2007


Hi:

There's a new Software Defined Radio by RF Space, makers of the SDR-14, 
called the SDR-IQ.  The two key differences are that the new radio will 
tune down to something like <500 Hz (that's NOT kHz, but Hz) and so will 
work for LORAN-C and other low end stuff.  The -IQ model has a 190 kHz 
bandwidth whereas the -14 has a 4 MHz bandwidth.

The -IQ has resolution bandwidths down to 0.031 Hz which might make it 
interesting for the FMT?

There's talk of a sync input to allow for pulsed signals.

http://groups.yahoo.com/group/SDR-IQ/
http://www.rfspace.com/sdriq.html

Using DSP technology might result in a higher accuracy timing receiver?

Have Fun,

Brooke Clarke

w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com



Rob Kimberley wrote:

>>From my Austron days (and I'm sure technology may have moved a bit since
>then), we always reckoned on about 1 microsecond as a fairly good accuracy
>for a standalone LORAN-C timing receiver. 
>
>Rob Kimberley 
>
>-----Original Message-----
>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>Behalf Of John Ackermann N8UR
>Sent: 20 January 2007 12:57
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] US considers shutting down Loran
>
>Hal Murray said the following on 01/19/2007 11:12 PM:
>  
>
>>From http://www.fcw.com/article97298-01-08-07-Web
>>
>>    
>>
>>>Norman said the Alliance for Telecommunications Industry Solutions 
>>>(ATIS), whose membership includes all the telecom carriers in the 
>>>country and equipment vendors, views eLoran as the "only viable 
>>>alternative to GPS for providing [Coordinated Universal Time] of day 
>>>and frequency accuracy that is suitable for a telecom primary 
>>>reference source."
>>>      
>>>
>>How good is Loran for timing?  What's the right parameter for "good"?
>>    
>>
>
>When used for frequency measurement, Loran is good to parts in 10e-13/day --
>ie, not much worse than GPS.  Of course, that's referenced to the Cesium
>clock at the Loran station, so you need to do a little juggling to trace
>back to NIST.  I believe that as they enhance the stations to the new
>hardware, the discrepancy from NIST will be much less.
>
>I recently got one of the (relatively rare) Austron 2100-T Loran receivers
>that do timing; you basically lock the receiver to one of the periodic Loran
>pulses that coincides with a UTC second marker and it generates a PPS signal
>tracking that.  I haven't had a chance yet to run any long-term experiments
>to measure its stability, but that's on my list of things to do.  (I also
>plan to hook it up as a refclock for an NTP server; I'm not sure if there's
>another Loran-based stratum 1 server out there today.)
>
>John
>
>John
>
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