DRAKE TR270 Owner'S Manual Download Page 38

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THE AMATEUR SATELLITES - MODES AND FREQUENCIES

As of this printing, there are currently four available
amateur satellites which will support communications
with the properly configured TR270 transceiver. Three of
the four satellites are 9600 BAUD AFSK data types and
the fourth supports FM voice operation. The following
table outlines the operating frequencies and modes of
these satellites.

Table 1:

Satellite

Downlink

Mode

Uplink

Frequency Frequency

(MHz) (MHz)

UO-22

435.120 FM, 9600 Baud

data

KO-23

435.175 FM, 9600 Baud

data
KO-25

435.175 FM, 9600 Baud

data

436.500

AO-27

436.800 FM, Voice

There are many other possible satellites to “work”
(communicate with) such as the SAREX (Shuttle Amateur
Radio Experiment) Space Shuttle, the Russian orbiting
space station MIR, etc. The TR270 is factory pro-
grammed with most of the common satellite frequen-
cies, as listed by Table 2. A total of 100 satellite memo-
ries are available to be programmed as desired. The
future should permit a large advancement in amateur
satellite operation with the launch of Phase 3D. Refer to
AMSAT for the latest details on all of the amatuer
satellites.

Table 2:

Assuming that the required antenna system is in place to
receive the desired satellite, an understanding of how to
configure the TR270 for voice and/or data communica-
tion through the satellite is required.

DOPPLER FREQUENCY SHIFT CORRECTION

Communication through a satellite requires an under-
standing of Doppler shift. An example of Doppler shift is
the “approaching train” phenomenon. As the train
approaches, its horn sound is high in pitch. As the train
passes and moves farther away, the pitch of the horn
changes to a lower frequency. Similarly, the signal
received from the satellite will start at a higher fre-
quency than the published (center) operating fre-
quency as the satellite approaches your location. As
the satellite passes over your location and moves farther
away, the frequency will change to a value lower than
the published (center) operating frequency. To counter-
act this shift, the TR270 incorporates a method of “lock-
ing” onto the satellite’s frequency upon AOS (acquisition
of signal) and continuously corrects the receiver fre-
quency throughout the pass until LOS (loss of signal) is
encountered. Additionally, the TR270 incorporates a
scan range search setting for automatic acquisition of
the downlink frequency, a scan pause setting to adjust
the rate of scanning, and a scan resume setting to
restart a scan if the downlink signal is lost.

FM VOICE OPERATION WITH A SATELLITE

For example, to work the AO-27 satellite:
From Table 2, note that Memory Channel 09 selects
AO-27 voice frequencies.

1. Enter the SETUP menu and select SETUP #15 = ‘3’. This
action will configure the TR270 for separate transceiver
‘A’ and receiver ‘B’ antennas. Also, if using an in-line
70 cm preamplifier, select SETUP #01 = ‘1’ to enable DC
power to the ‘ANTENNA 2’ rear panel connector. Press

the

SETUP

button to exit the SETUP menu.

2. Press the

SAT

button to enter the satellite mode. The

TR270 will display the factory programmed satellite

memories. Press the

buttons to select memory

‘09’. Refer to Figure 12 on the following page.

3. Press the

P. OUT

button to select the required transmit

power level: Low, Medium, or High.

In the Satellite mode, transceiver ‘A’ displays the
transmit frequency, and receiver ‘B’ displays the receive
frequency. To alter the contents of a particular memory

channel, if desired, rotate the tuning wheel or press

NUM

followed by numeric frequency entry to tune either

transceiver ‘A’ or receiver ‘B’, as selected. Press the

A / B

button to select transceiver ‘A’ or receiver ‘B’, as
required. To store these new frequencies, if desired,

press the

STORE

button followed by the

MEM

button and

enter the desired 2-digit memory number using the
numeric buttons (this operation automatically shifts to
the NUM mode).

145.900
145.975
145.850
145.900
145.870
145.980
145.870
145.980
145.850

Satellite Operation, continued 33

Uplink

Frequency

(MHz)

145.900
145.975
145.850
145.900
145.870
145.980
145.870
145.980
145.850
145.850
145.925
145.980
145.870
145.550
144.490
144.910
144.930
144.950
144.970
144.990

Satellite

Channel

Memory

Number

00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19

Satellite

UO-22
UO-22
KO-23
KO-23
KO-25
KO-25
KO-25
KO-25

AO-27
AO-27

POSAT
POSAT

FO-29

MIR

SAREX
SAREX
SAREX
SAREX
SAREX
SAREX

Downlink

Frequency

(MHz)

435.120
435.120
435.175
435.175
435.175
435.175
436.500
436.500
436.800
436.800
435.275
435.275
435.910
145.550
145.550
145.550
145.550
145.550
145.550
145.550