Quantar Linking

There are a few ways to link Quantars, using p25nx, mmvdm, and the method presented here using astro tacs.

Quantars were designed to be "linked" only as a simulcast or linked receiver network for a single system. This is accomplished by connecting the wireline for analog and the v.24 for digital. Quantars may be linked back-to-back by using a v.24 cross over and connecting the wirelines between them. While this is the simplest way, it doesn't scale. Using an ASTROTAC comparator to sit between the Quantars as a network switch function.

Each Quantar needs a two links to the ASTRO-TAC, a v.24 and a wireline link. If all Quantars are at the same site, this is really easy to do, just connect the wirelines and v.24's using cross overs. In the early 1990's the v.24 and wireline interfaces made quite a bit of sense, the v.24 and wireline would plug directly into a channel bank, and the DS1 or fractional DS1's between sites was easy. As of today, T1's are hard to find and very expensive. Channel banks are thousands of dollars on the used market now.

Today the internet is ubiquitous and linking via IP is the preferred method. This means we must transport synchronous serial and analog voice for each Quantar back to a central site. There are a few ways to do this via IP or MPLS, and presented here will be using cheap and easily available cisco routers in a VPN.

Network Planning

Lots of routers, lots of ports, lots of circuits. You will need to name and keep interfaces described or you will be unable to troubleshoot this network.

Reliable bandwidth and pps is required. The analog links will require about 60 kbit/s at 33 PPS at all times , stun is another 20 kbit/s when it's operating. A fully loaded 16 port ATAC3000 using all remote ports will be 1.280 Mbit/s at 1220 PPS or about a fully loaded T1.

network monitoring

A server with LibreNMS or Observium

SNMP

SSH for management