Vega DSP-223, Technical Manual

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Tone Remote 5
3 Level Settings
Once the unit is connected into the system, the level potentiometers can be set as shown in Table 1.
3.1 Line Receive Level Adjust Procedure
The line RX level is the first level that must be set because all of the tone decoding is based on this level.
Connect an Oscilloscope, RMS voltmeter, or dBm meter to Ground (TP-12) and Line RX audio (TP-2) test
points on the front of the
DSP-223.
Inject the known highest
signal level into the line
receive circuitry. An
external generator or a
console can generate
this with a test tone
capability. Using Table
1, find the value of the
injected signal level in
the left most column
(Actual RX Input (dBm)).
In the case of the DSP-
223 being connected as
a standard tone remote,
the MAX input +10dBm
column shows the level
to adjust the RX Line
Potentiometer to. This
assumes that the
st10dBm Guard
Tone will be used.
The DSP-223 must be
tuned to allow this
+10dBm signal to be
decoded without
overdriving the inputs
(max 3.5Vp-p) of the
Analog to Digital
Converter (ADC). On
the row of the injected
signal level, find the
column that matches the
measurement units of
the device attached to
the Line RX level test points on the front panel. Adjust the Line RX Potentiometer (R68) until it is close to
the value listed in the table. This will allow the unit to work over its entire range without saturating the
ADC. Note that this measurement is a signal level measurement of the voltage that is supplied to the
ADC used by the DSP to decode the various required tones.
3.1.1 Revision G PCB’s with J17
Starting with PCB Revision G, jumper J17 has been added to provide a wider decode range. With J17 in
the “A” position the DSP223 will perform like previous versions. When J17 is in the “B” position, a 6dbm
gain is added to the input of the ADC after PTT is engaged.
Setup is different with J17 in “B”. When the DSP223 is in PTT, adjust the Line RX Potentiometer (R68) for
–15dbm at Line RX audio (TP-2) test point.
Table 1
Actual
RX
Input (dBm)
Vrms Vpp dBm Vrms Vpp dBm dBm Vpp Vrms
10 1.13 3.20 3 10 6.90 2.44
9 1.02 2.88 2 9 6.25 2.21
8 0.92 2.60 1 8 5.60 1.98
7 0.79 2.24 0 7 5.00 1.77
6 0.74 2.08 -1 6 4.50 1.59
5 0.68 1.92 -2 5 4.00 1.41
4 0.62 1.76 -3 4 3.60 1.27
3 0.55 1.56 -4 3 3.20 1.13
2 0.51 1.44 -5 2 2.88 1.02
1 0.40 1.14 -6 1 2.60 0.92
0 0.36 1.02 -7 1.13 3.20 3 0 2.24 0.79
-1 0.33 0.92 -8 1.02 2.88 2 -1 2.08 0.74
-2 0.29 0.81 -9 0.92 2.60 1 -2 1.92 0.68
-3 0.26 0.74 -10 0.79 2.24 0 -3 1.76 0.62
-4 0.22 0.63 -11 0.74 2.08 -1 -4 1.56 0.55
-5 0.20 0.56 -12 0.68 1.92 -2 -5 1.44 0.51
-6 0.18 0.52 -13 0.62 1.76 -3 -6 1.14 0.40
-7 0.16 0.46 -14 0.55 1.56 -4 -7 1.02 0.36
-8 0.14 0.41 -15 0.51 1.44 -5 -8 0.92 0.33
-9 0.13 0.37 -16 0.40 1.14 -6 -9 0.81 0.29
-10 0.12 0.34 -17 0.36 1.02 -7 -10 0.74 0.26
-11 0.11 0.30 -18 0.33 0.92 -8 -11 0.63 0.22
-12 0.10 0.28 -19 0.29 0.81 -9 -12 0.56 0.20
-13 0.09 0.25 -20 0.26 0.74 -10 -13 0.52 0.18
-14 0.22 0.63 -11 -14 0.46 0.16
-15 0.20 0.56 -12 -15 0.41 0.14
-16 0.18 0.52 -13 -16 0.37 0.13
-17 0.16 0.46 -14 -17 0.34 0.12
-18 0.14 0.41 -15 -18 0.30 0.11
-19 0.13 0.37 -16 -19 0.28 0.10
-20 0.12 0.34 -17 -20 0.25 0.09
Table Usage:
1) Place a known signal level into the RX terminals of the Vega device being setup.
2) Determine the maximum signal level that the device will see. This table su10 and 0 dBm
3) Using the values from #1 and #2, Lookup #1 in the left column and move to the grouping for #2
4) Set the RX pot for the value in the table
dBm to Volts Table
RX POT Setup for Vega DSP Based Products
Direct Crossover Max Input +10dBm
Set RX To:
Max Input 0dBm
Set RX To: