AstroTAC receiver

Astro Spectra · Post by **Astro Spectra** » Tue Oct 23, 2001 12:24 am

In my line of work we use Quantar repeaters. I'm reasonably familiar with both the hardware and RSS.

However I recently ended up with a spare AstroTAC receiver and I'm wondering about using it in a repeater set-up.

Has anyone done this and if so where did you find a COR or PTT output (other than the front panel LED)?

FYI the wireline board is combined with the PSU and is AstroTAC specific.

Salem The Cat · Post by **Salem The Cat** » Tue Oct 23, 2001 2:31 am

On 2001-10-23 04:24, Astro Spectra wrote:
In my line of work we use Quantar repeaters. I'm reasonably familiar with both the hardware and RSS.

However I recently ended up with a spare AstroTAC receiver and I'm wondering about using it in a repeater set-up.

Has anyone done this and if so where did you find a COR or PTT output (other than the front panel LED)?

FYI the wireline board is combined with the PSU and is AstroTAC specific.

HELLLLLOOOOOO.....it's a RECEIVER ! what
are you going to PTT ??? Typically you'd
use it in a voting system, and the comparator
is tasked with providing key up commands to
the transmitter. The Astrotac receiver is
just that - a receiver....it won't do you
any good without a comparator to feed it's
output into.

Astro Spectra · Post by **Astro Spectra** » Thu Oct 25, 2001 4:35 pm

I guess when you want a job done properly you just gotta do it yourself....

J11 pins 5 and 6 close when the COR operates. Pin 5 is the Aux out (RDSTAT) relay common contact and pin 6 is the normally open contact. This PTT output is hooked to the MSR keying line and ground.

I've used the AstroTAC receiver to replace the old 25 kHz wide receiver in an MSR2000 repeater. Aligned the MSR transmitter deviation for +/- 2.5 kHz and programmed the AstroTAC for one of our new 12.5 kHz channels. Instant narrow band mandate compliance.

Just needed imagination.

Post by **vcaruso** » Thu Oct 25, 2001 7:06 pm

Astro,

You are correct in both the use and the fact that one just needs a little imagination. Apparently Salem dosent quite grasp the concept of how a comparitor knows that there is a signal coming in on the receivers, COR is COR whether its a multi site voter set up or a simple repeater it is still needed. I guess perhaps all the systems he has worked on operate on VOX only?

Salem The Cat · Post by **Salem The Cat** » Fri Oct 26, 2001 6:41 am

On 2001-10-25 23:06, vcaruso wrote:
Astro,

You are correct in both the use and the fact that one just needs a little imagination. Apparently Salem dosent quite grasp the concept of how a comparitor knows that there is a signal coming in on the receivers, COR is COR whether its a multi site voter set up or a simple repeater it is still needed. I guess perhaps all the systems he has worked on operate on VOX only?

No actually all our customers operate in
full Astro mode using the 9.6 modems over
a spread spectrum T-1 hop to the ATAC.

Have never encountered one being used on
an analog 25khz wideband channel.

Live and learn though....

Astro Spectra · Post by **Astro Spectra** » Fri Oct 26, 2001 2:27 pm

For those not familiar with the Quantar family you can set the receiver bandwidth for 30/25/12.5 kHz and the mode to FM, Securenet or Astro. In Astro mode it does not decode to audio but does allow limited mapping of talkgroups. The AstroTAC output can be either analog (only for FM modes) or in Astro mode RS-232 with an internal 9.6 kbps wireline modem option.

The AstroTAC is really just half a Quantar. The system controller and receiver modules are exactly the same while the wireline board is a bit limited.

What I found very interesting is that you can actually program an AstroTAC as if it were a Quantar by changing the station type from AstroTAC to Base. There is a selection of other equipment configurations that you can choose, either working to an AstroTAC Comparator or another Quantar.

Unlike most Moto RSS you can happily create codeplugs for hardware you don't have and for unsupported frequencies. OK so you get some alarms on the equipment if there isn't a transmitter or power amplifier present!

Anyway in my case it would be a bit of a waste using it a 25 kHz channelled receiver but for the new 12.5 kHz channels this spare AstroTAC got us up and running.

RFdude · Post by **RFdude** » Wed Oct 31, 2001 4:09 pm

Do you guys have any ideas why the AstroTac/Quantars don't implement dual voting (DIVERSITY) receivers? At VHF they are not available. A second receiver card can be plugged in, but that is for a different band split. The controller schematics seem to suggest that all the hardware for diversity voting between two rx's exists, leaving it as a firmware issue. The local FD (800 MHz) has also confirmed the lact of diversity. This seems odd considering most other mobile technologies use diversity receivers, and Morotola's own iDEN seems to use triple diversity (I'm told?).

Can anyone shed some light?

<font size=-1>[ This Message was edited by: RFDude on 2001-10-31 23:08 ]</font>

Astro Spectra · Post by **Astro Spectra** » Thu Nov 01, 2001 12:27 am

A very good question.

I've tried two receivers in a Quantar but the Qunatar I tried did not have new enough firmware to support the dual receiver set-up.

However while the RSS will let you set up the second receiver frequency I can't find a page to define what to do with the second receiver!

Salem The Cat · Post by **Salem The Cat** » Thu Nov 01, 2001 2:44 pm

Typically if it's a decent antenna system,
or a tower with gain antennas, and TTA's in
the system design (even without it)...the
performance gain afforded by diversity isn't
worth it for conventional LMR applications.

Although, in a digital system, it seems like
a good idea that certainly wouldn't hurt to
implement.

The second receiver is used for switching to
a different preselector for freqs outside the
bandwidth of the first one (in order to avoid
losing performance with a detuned front end).

SeanF · Post by **SeanF** » Wed Nov 14, 2001 4:43 pm

I could be wrong but it was my understanding that despite the "Astro" name in an AstroTac receiver, what is required to operate Astro Digital with a Quantar repeater is in fact, a "Digitac" receiver.

Twisted_Pear · Post by **Twisted_Pear** » Thu Nov 15, 2001 12:37 am

On 2001-11-14 19:43, SeanF wrote:
I could be wrong but it was my understanding that despite the "Astro" name in an AstroTac receiver, what is required to operate Astro Digital with a Quantar repeater is in fact, a "Digitac" receiver.

IIRC,

SpectraTAC = analog
DigiTAC = 12kbit encryption
ASTROTAC = digital

aaron_tech · Post by **aaron_tech** » Wed Dec 05, 2001 10:59 am

spectyra tac has been phased out and replaced by the digitac ibelieve. I ahve analog conventional unencrypted simulcast system that use digitacs

JohnG · Post by **JohnG** » Wed Dec 05, 2001 7:53 pm

Despite the age of the product, analog Spectratac is alive and well. Securenet capable Spectratac was phased out when Digitac was introduced in the mid 1980's.