[OZAPRS] Calibration Signals

Sun Nov 19 19:17:41 AEDT 2017

Andrew

OFDM is fairly  new but been around for awhile on APRS. Works great on HF, works much better than FSK, but not much adoption here, mainly EU and some USA stations..

Regards

Pete

For others who may be interested in the detail..

https://www.sigidwiki.com/wiki/Robust_PACKET

Sent from my Windows 10 phone

________________________________
From: OZAPRS <ozaprs-bounces at aprs.net.au> on behalf of Andrew Rich <vk4tec at tech-software.net>
Sent: Sunday, November 19, 2017 4:13:11 PM
To: Australian APRS Users
Subject: Re: [OZAPRS] Calibration Signals

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://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fwb2osz%2Fdirewolf%2Fblob%2Fmaster%2Fdoc%2FRaspberry-Pi-SDR-IGate.pdf&data=02%7C01%7Cvk3tbn%40hotmail.com%7C0bc9413bcba944009e1708d52f0c466a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636466652135705756&sdata=VbpuXmu21bhlpUJigD0FuRBj%2FrY%2FgN%2FM6yhVMgqBH3Y%3D&reserved=0
>>
>>
>>        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://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fkhaytsus%2Fdirewolf-init&data=02%7C01%7Cvk3tbn%40hotmail.com%7C0bc9413bcba944009e1708d52f0c466a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636466652135705756&sdata=UxVgQyZdu5S8L85%2BUnwuqt8xLTkn2Tyxwjlaj1Siirc%3D&reserved=0 )
>>
>>        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
>>
>>            https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.livingwaters.com%2Fgood&data=02%7C01%7Cvk3tbn%40hotmail.com%7C0bc9413bcba944009e1708d52f0c466a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636466652135705756&sdata=LRlzhXIIEYmOv960FNIN9rSJsCSJRJ1Nd2l3xZzQq8s%3D&reserved=0   |
>>        https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fvk6hgr.ampr.org%2F&data=02%7C01%7Cvk3tbn%40hotmail.com%7C0bc9413bcba944009e1708d52f0c466a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636466652135705756&sdata=hsqoJZ88gVjo1jzyO4uK4w5avdnDiLCKk8YWww%2FxA0g%3D&reserved=0
>>
>>                       MSN/Skype/Email: grogers at vk6hgr.echidna.id.au
>>        <mailto:grogers at vk6hgr.echidna.id.au>
>>
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>>
>>
>>
>> --
>> Gavin Rogers mobile
>>
>>
>>
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