[OZAPRS] Calibration Signals

[Andrew Rich]

Just seeing if your paying attention

Orthaganol Frequency Division Multiplexing 

New APRS mode ?

A

> On 19 Nov 2017, at 2:40 pm, Glen English VK1XX <glenlist at pacificmedia.com.au> wrote:
> 
> 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
>> 
>> 
>> 
>> _______________________________________________
>> OZAPRS mailing list
>> OZAPRS at aprs.net.au
>> http://lists.aprs.net.au/mailman/listinfo/ozaprs
> 
> 
> _______________________________________________
> OZAPRS mailing list
> OZAPRS at aprs.net.au
> http://lists.aprs.net.au/mailman/listinfo/ozaprs