The recalled data is then tested for validity. If the data proves invalid, it is
bypassed and re-tuning is performed. If the data recalled proves valid, the data
is sent to the relays and the VSWR is checked. If the VSWR is less than 2:1, the
program branches to the "OK Tuned" section of the program. If the VSWR is
found to be greater than 2:1, the program branches to the "re-tune" program.
Several tests are made to determine which tuning algorithm or path should be
used to tune the coupler. These tests are based on frequency, antenna input
impedance, antenna phase, and VSWR. Numerous subroutines are executed
repeatedly, depending on the status of the criteria mentioned above, in order
to achieve proper tuning.
Should the initial primary tuning sequence prove unsuccessful, secondary
algorithms are attempted until all possible routines have been exhausted. If, at
this point, an acceptable VSWR has not been achieved, the tuner status acqui-
sition time is increased, and the tuning process is repeated.
If, after the second attempt, the tuner still cannot achieve a proper VSWR, the
program branches to a "no-tune" program. Here, the tune indicators will
blink on and off, all tuning elements will be removed, and the tuner will go
into a 20 second time delay. During this time delay, the transmit frequency is
monitored. Should a change in frequency occur, the tuner will revert to the
beginning of the interrupt segment of the program and attempt to tune the
new frequency.
If the tuner achieves a good VSWR during the tuning sequence, the program
branches to the "OK Tune" section of the code. Here, the tune indicators are
engaged. A test is then made to check if 'J3' is set to tune from memory. If so,
the frequency is measured and the tuning elements used are saved in memory
coupled with a verification code.
Once saved, a test is made on 'J2' to check if the duplex mode has been selected.
If so, the transmit tuning elements remain in circuit until the receive mode is
verified. At this time all tuning elements are removed.
The current frequency is then saved for future comparison and the computer
reverts back to the "sleep" mode.
9
9..2
2
T
TU
UN
NIIN
NG
G A
AL
LG
GO
OR
RIIT
TH
HM
MS
S O
OR
R P
PA
AT
TH
HS
S
As mentioned previously, various tests are executed to determine the most logi-
cal tuning sequence to be performed. Dependent on the test results, additional
57
© 1998 SGC Inc
SG-235 Manual
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA 98005 USA
P.O. Box 3526, 98009 Fax: 425-746-6384 Tel: 425- 746-6310 or 1-800-259 7331
E-mail: [email protected] Web site: http://www.sgcworld.com