PW> ? I was in my local supermarket ( Safeway ) the other week and whilst
 PW> loading my trolly, I noticed a chap with a hand held tranceiver
 PW> clipped to his belt - ( It looked like a VHF unit although I couldnt
 PW> get near enough to read the frequency display ! )
 PW> The radio was making a familier buzzing sound every couple of
 PW> seconds,this sounded just like Packet radio. The radio was attached
 PW> to a barcode scanner which he was using this on the goods on the
 PW> shelves, so i suppose he was stock taking.
 PW> I just wondered if anyone knew which part of the radio spectrum was
 PW> being used for this job. Also would it be standard AX25 packet like
 PW> Radio Hams use ?
Well, I'm not sure about the exact nature of the unit you describe.
However, at the supermarket where I work, we have hand-held radio units
that are similar.
They have an attached bar code reader and send data to and from an IBM PS/2
connected to a wall-mounted tranceiver. Frequency is 461.0875 Mhz. and mode
is simplex. The wall unit sends a morse code ID around every 15 minutes
which freezes the hand-held unit's display and transmitter until it
finishes and then the handshaking resumes.
The system is used mainly for receiving where vendors' items are scanned
and amount received is entered and the data is stored for record keeping
and receipt invoices are printed out for attachment to vendor invoices
which are passed on to the main office for billing/payment/accounting.
It can also be used for checking the current price on vendor items when
doing inventory.
I've listened to the frequency and it sounds a lot like tcp/ip the way my
modem's receive and transmit lights blink when I'm connected to the
internet.  THUMPthump THUMPthump.... brAAAAAAAAAP... THUMPthump...
Considering the small size of the antennas (2 inches), I'm surprised that
I am able to receive it as far as a quarter mile away.
Also, these units emit no audible sound other than a beep when it scans
something.
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