10
Description
T801-4 Installation and Operation Manual
© Tait Electronics Limited September 2007
1.1
Functional Description
The T801-4 GPS frequency reference is an essential frequency reference for
all TB8100 and TB9100 base station products when they are used in
simulcast applications (for example, TaitNet QS
2
). It is based on the Dalman
Satsync 7 module, which uses the Coordinated Universal Time (UTC)
pulses derived from the US Global Positioning System (GPS) as an accurate
and stable reference source. Frequency stability is achieved by locking an
internal “master” oscillator to a 1 Pulse Per Second (1PPS) timing standard
derived from the GPS via a GPS receiver. The T801-4 is fitted with one or
two Satsync 7 modules, depending on the model (refer to
“Identifying the
T801-4” on page 12
).
The T801-4 provides up to eight frequency outputs in the range 50Hz to
25MHz. It has the option of using an internal and/or external GPS
receiver. The internal receiver is the Trimble Lassen iQ GPS receiver
module, and the external receiver is the Dalman 40742 GPS antenna/
receiver
1
, which has the GPS receiver integrated with the antenna. If both
options are used, the T801-4 has the ability to change over to the “standby”
receiver if the primary GPS receiver fails.
The T801-4 also provides the 1PPS signal from the GPS receiver(s) as TTL
(50
Ω
) and RS-485 signals. These 1PPS outputs can be disabled if the GPS
“fix” becomes invalid.
The Satsync 7 module is programmed and monitored with the Dalman
Engineering Terminal (ET) PC software. Program access to the module is
provided by an RS-232 port on the front panel.
Internal DC-DC converters take the externally provided 10.5VDC to
28VDC input and convert it into the 12VDC required by the internal
modules. One converter is provided for each Satsync 7 module.
The T801-4 is packaged in a standard 19 inch 1U chassis. The
programming port and alarm LEDs are on the front panel, while all other
inputs and outputs, including DC power, are on the rear panel.
1. Available under the product code T801-40-0000.
