[OZAPRS] Calibration Signals

[Glen English VK1XX]

I think you have a typo, Andrew, I think you meant to type 3G , not 4G

Yes, 3G uses CDMA and requires critical relative timing references for
scrambling code chip offsets. For a chip rate of 3.84 Mcps, or a very
small fraction of the cycle time of 260 nS.

(4G uses OFDM. Timing requirements for OFDM are on OFDM frame boundaries
which are quite slow in order of (1/15e3) + guard band.)



On 19/11/2017 3:33 PM, vk4tec at tech-software.net wrote:
>
> 4G should be very good
>
>  
>
> They have some of the best frequency and time standards
>
>  
>
> They have to because of the CDMA modulation
>
>  
>
> Andrew
>
>  
>
> *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au] *On Behalf Of *Gavin
> Rogers
> *Sent:* Sunday, 19 November 2017 2:27 PM
> *To:* Australian APRS Users <ozaprs at aprs.net.au>
> *Subject:* Re: [OZAPRS] How to make a raspberry pi satgate for the ISS
>
>  
>
> Maybe different in other states, but in Perth the only carrier with
> GSM still is Vodadone, and their coverage isn't good enough where I am
> to get a good calibration.
>
>
> On 19 November 2017 11:21:49 am AWST, Peter VK2MPJ
> <vk2mpj at yahoo.com.au <mailto:vk2mpj at yahoo.com.au>> wrote:
>
>     I’m curious why you say that using kal and a GSM signal is not
>     possible anymore?
>
>     I did this locally just last weekend…
>
>      
>
>     2MPJ
>
>      
>
>
>
>         On 19 Nov 2017, at 12:42 pm, Gavin Rogers
>         <grogers at vk6hgr.echidna.id.au
>         <mailto:grogers at vk6hgr.echidna.id.au>> wrote:
>
>          
>
>         On 19/11/2017 9:30 AM, vk4tec at tech-software.net
>         <mailto:vk4tec at tech-software.net> wrote:
>
>              
>
>             Or, as i've mentioned before, just link to the existing
>             Direwolf SDR+APRS guide, which covers off setting up an
>             igate pretty
>             well: https://github.com/wb2osz/direwolf/blob/master/doc/Raspberry-Pi-SDR-IGate.pdf
>
>
>         In this guide, there's a link to a script that will tune to a
>         NOAA frequency and re-calibrate an SDR TV stick
>         ( https://github.com/khaytsus/direwolf-init )
>
>         What would be a good high-stability signal source here in VK
>         for the calibration? I used to use the kal program to
>         calibrate against GSM transmitters, but that's not possible
>         any more. I'd think the trunking control channel for an
>         emergency services' channel would be stable, strong and always
>         on? Or DAB+ transmitter, or..?
>
>
>         73
>         Gavin.
>
>          
>
>         -- 
>
>          
>
>               Gavin Rogers                     |  Amateur radio
>         station VK6HGR    
>
>             http://www.livingwaters.com/good   |    
>         http://vk6hgr.ampr.org/
>
>                        MSN/Skype/Email: grogers at vk6hgr.echidna.id.au
>         <mailto:grogers at vk6hgr.echidna.id.au>
>
>         _______________________________________________
>         OZAPRS mailing list
>         OZAPRS at aprs.net.au <mailto:OZAPRS at aprs.net.au>
>         http://lists.aprs.net.au/mailman/listinfo/ozaprs
>
>      
>
>
> -- 
> Gavin Rogers mobile
>
>
>
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