RF data link good for 6 - 9 KM's??? (farm application)

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 I seem to recall a change (some years back)
 to ACA's UHF CBRS reg's, that permitted (eg,
 agricultural indutries) the use of [CBRS] to
 remotely control farm processes (eg, switch-
 ing On or Off as pump), ie, by sending con-
 trol signals by radio.

 What are the specifics of the -permitted-
 data control signals? (Eg, were digital modes
 ever authorized? Or maybe just analog tone-
 sequence?)

 I think there were limits om how often a
 control signal could be sent... If so,
 details?

 Where are the ACA's ref doc'ts on the topic?

 TIA




Re: RF data link good for 6 - 9 KM's??? (farm application)


Hmm, I heard of this as well but I can't find anything with Google.

I'm pretty sure you were only allowed to use DTMF tones with a limited
duty cycle (2 seconds transmit per 30 mins or something similar)

I'm sure if you contact the ACA they can provide you with further info.


Re: RF data link good for 6-9 KM's (farm appl'n) - ACA reg excerpts



 Thanks.

 I just found it in a CBRS Class License document
 at the ACA's web site.

 Of course, their site search tool didn't help...

 OUR TAX DOLLARS AT WORK... keeping sloppy web
 programmers comfortable in ACT or NSW, I bet,
 but NOT GETTING THE JOB DONE.

 The Site Map got me to the right document
 (after a few false hits...); here's an
 excerpt or three:

 First, from "Radiocommunications
 (Citizen Band Radio Stations) Class Licence 2002"
 - cbrs.rtf or .pdf - we have:

 "5 Class Licence
    Subject to sections 6, 7, 8, 9, 10 and 11,
    a person may only operate a CB station that:

    (a) directly transmits speech to, or
        audio tones to initiate communication with,
        another CB station:

         (i) on a carrier frequency mentioned
             in item 1, 2, 3, 4 or 5 in Schedule 1; and

        (ii) subject to a restriction mentioned in the item; or

    (b) through a CB repeater station, transmits speech to, or
        audio tones to initiate communication with,
        another CB station:

         (i) on a carrier frequency mentioned in item 5
             in Schedule 1; and

        (ii) subject to a restriction mentioned in the item;
             or

    (c) transmits data to communicate with another CB station:

         (i) on a carrier frequency mentioned in item 6
             in Schedule 1; and

                  (ii)    subject to a restriction mentioned in the item."

 -and-

 [Sec     Ch       Freq,MHz]"6
     22

      23
     476.950

      476.975
     A transmitter employed in a CB station:

         (a)  must operate with a transmitter power not exceeding 5 watts;
and

         (b)  must not exceed an EIRP of 8.3 watts; and

         (c)  must operate with an occupied bandwidth not exceeding 16 kHz;
and

         (d)  must not exceed a carrier frequency error of 3 kHz; and

         (e)  must not exceed an adjacent channel power of -22 dBm; and

         (f)  must not exceed a conducted spurious emission of -30 dBm; and

         (g)  must operate on a duty cycle of not more than 3 seconds in any
period of 60 minutes; and

         (h)  must be fitted with a device that shuts the transmitter down
after 3 minutes of continuous operation.

      A receiver employed in a CB station must operate with a conducted
spurious emission not exceeding
      -57 dBm.

      Note   The use of single frequency store and forward repeaters is
permitted.



 From elsewhere, we have:

 "5.10 Call tone facility

    If a call tone facility is provided on the equipment,
    it must not last (sic) longer than 3 seconds
    in any 60 second period."

  - From: "Radiocommunications
                      (UHF CB Radio Equipment) Standard 2004"

 "Uses not permitted

  Other types of data operation, such as Packet Radio,
  are not permitted on CB bands.

    [So, if you're disability precludes you
    from speaking, then Citizens Band Radio
    is not for you - at least in Australia;
    get an Amateur Radio License...  ;-) ]

  Voice communications is not permitted on UHF CB
  channels 22 and 23.

    [Tell that to a local gov't department...]

  Telemetry and telecommand is not permitted on
  any channel other than UHF CB channels 22 & 23"

  The above is from a web page with title:

   "Class Licensing
    Citizen Band Radio Stations"

      [Remember when "CBRS" meant:
      "Citizen Band Radio SERVICE"?

      Well, it still is - at least
      in the country, where people
      still help each other, mostly.

      It's just gov't that wants us
      to "compete" with each other,
      eg, buying ourselves poor or
      looking after ONLY ourselves]

 [ The usual DISCLAIMER: I'm NOT a lawyer :-) ]

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Re: RF data link good for 6 - 9 KM's??? (farm application)



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Yes. Data is permitted (I think voice is prohibited?)
on channels 23 and 24 (or is it 22 and 23? :).

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I imagine there would be but providing you're not
sending an almost constant string I wouldn't
worry too much about it - I doubt the ACA do!

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If you can find anything on the ACA's website
you're doing very, very, very well.

Essentially if you use standard commercial
UHF CBs and something like DTMF as the tone
system you won't go far wrong. You may need
to pay attention to your antennas to get good
range - consider a Yagi, at least at the Rx end.

Mike Harding


Re: RF data link good for 6 - 9 KM's??? (farm application)


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The class license document contais errors and is too hard to understand.

The information paper is much more informative and useful:
http://internet.aca.gov.au/ACAINTER.524644:STANDARD:480903640:pc=PC_1265

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You can only transmit telemetry/telecommand on UHF channels 22 and 23 and
voice is prohibited on those channels.  You are limited to a 3 sec duty
cycle, which means you can only transmit for 3 sec in any 60 sec window.
Data transmission is allowed but packet radio is not - which in my opinion
means you can use a radio modem provided it is non-routable (ie. it is used
for direct point to point communications only).

On UHF channels 22 and 23, you are limited to 5W antenna input power and an
EIRP of 8.3 watts so a lower gain yagi would be fine on the tx end also. The
increased EIRP does not apply to other channels.








What gear for RF rem cont good for 6-9 KM's? (farm appl'n)


 OK, so we know we can use UHF CB Ch 22 & 23
 for up to 3 seconds out of every 60 seconds
 for remote control applications (cf post 3)

 So, who's making AFFORDABLE gear that can
 be EASILY interfaced with a PIC-based board?

 Maybe someone has a cheap but reliable sys-
 tem that combines a (eg, used FM-92) radio &
 a PIC controller board, with isolated inputs
 & relay-controlled outputs that can be pro-
 grammed by a cluey user or their consultant?

 Are there any used gear on the market or
 coming soon (eg, after some soon-to-hit-the-
 market new ver of an existing model arrives)?

 TIA

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Re: RF data link good for 6 - 9 KM's??? (farm application)



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A possible solution using 477MHz UHF CB was described in Silicon Chip
Feb 2005 p. 72 - 78. According to Stan Swan ACA rules specify external
antennas can be connected to UHF CB radios.

http://www.siliconchip.com.au/cms/A_103804/article.html

Re: RF data link good for 6 - 9 KM's??? (farm application)


On Fri, 25 Mar 2005 08:48:44 GMT, Ross Herbert

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And I just recalled that in Silicon Chip Mar 2005 there was this
article http://www.siliconchip.com.au/cms/A_104060/article.html on
sending data over UHF CB using a Picaxe 08M.


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