Compact RDMS
TM
Telemetry Receiver
3
Quasonix, Inc.
1.2.2.2
Eight-way Clock and Data Multiplexer – 8F
Normally, the three clock and data streams available on the MDM-37 are Clock and Data A (the primary), Clock
and Data B (the secondary for asynchronous PSK modulations), and Clock and Data C (what would normally be the
primary for the combiner channel in a rack mount configuration).
The 8F option allows the user to designate what information comes out on these pins by way of an eight-way
multiplexer (MUX). (Though there are a total of four pairs of clock and data, there are only enough pins to allow
access to three pairs in the compact configuration.) This makes it possible for the information from the primary
Clock and Data to be copied to the secondary and tertiary set of outputs, giving the user three simultaneous copies of
the information.
The 8F option also requires the -37 option to be installed on the receiver.
1.2.2.3
Double Rate - DR
The DR option provides double-speed SOQPSK-TG (46 Mbps). This option extends the standard upper bit rate limit
from 23 Mbps to 46 Mbps
1.2.2.4
Ethernet Payload - EN
When the EN option is enabled, all transmitted clock and data signals are serialized Ethernet packets.
1.2.2.5
Adaptive Equalizer - EQ
The Adaptive Equalizer option in the Quasonix receiver improves reception in multipath channels by using digital
signal processing to compensate for the signal distortion due to multipath. This option is compatible with standard
telemetry applications and installations and it works with any brand of transmitter.
Multipath fading can seriously degrade the quality of wireless telemetry data. Radio transmissions can reflect off of
the airframe or other objects and arrive at the receiving antenna with different time delays, carrier phases, and
relative strengths. The sum of these multiple transmission paths can produce serious distortion and signal fading
resulting in poor data quality and long periods of data outage. Contrary to most situations, increasing the transmit
power will not improve the link quality and may actually make the situation worse. Narrowing the beamwidth of the
antenna may help eliminate some of the reflections and reduce the overall fading and distortion, but constraints on
dish size and antenna tracking performance impose beamwidth limits.
Another solution is to mitigate the effects of the multipath channel by applying a filtering operation at the receiver
that effectively undoes the distortion caused by the channel, thereby 'equalizing' the received signal. Since the
transmitter is typically moving relative to the receiver, the RF propagation environment dynamically changes over
time requiring the equalizer to 'adapt' to continually combat the perceived channel distortion. The 'adaptive
equalizer' automatically calculates and applies a compensating filter to the received signal that restores its ability to
be recovered by a traditional telemetry detector.
1.2.2.6
Extended Temperature - ET
The ET option specifies an extended operating temperature range (-40
°
C to +85
°
C).
1.2.2.7
Viterbi Decoder (for Legacy PSK Only) - K7
The K7 option (k=7, rate 1/2) enables Viterbi decoding of a convolutionally encoded data stream, which converts it
back to the original (uncoded) source data stream.
Convolutional encoding adds redundant information to the transmitted data stream to help detect and correct bit
errors that may occur, particularly due to predominantly Gaussian noise. Use of convolutional encoding requires a
matching Viterbi decoder in the receiver to extract the source data. The decoded data rate is half the encoded data
rate.