Sonifex HY02 DIGITAL, User Handbook Manual

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Page 2-6 Circuit Description & Controls
HY02 Digital TBU User's Guide
The ringing detector can be set to auto answer after 1 to 5 ring tone bursts by means
of RV3.
2.2.7. Dial Tone Detectors
Dial tones presented to the equipment at the termination of a call, ( hang up tone )
can be detected by the equipment and can be used to disconnect the HY02 Digital from the telephone
line as an automatic process.
Since there are several hang-up tones in use worldwide, there are jumper settings at
JP8, JP9 and JP10 to select the various possibilities :
a) Single or dual tones
b) Pulsed or continuous tones
c) Long or short cadences.
The tone frequencies are detected by two independent tone decoders Q33 and Q34
each with centre frequency setting presets RV2 at 350 Hz and RV1 at 440 Hz.
Detected signals are processed by the logic at Q35 and present an unlatching signal
to the disconnect circuitry at Q22.
Alternatively when the caller hangs up the line voltage increases. This is detected by
Q27 and coupled by opto-isolator Q21 which creates a disconnect signal at Q22. This disconnection is
the K break.
2.2.8. Displays
There are two LED indicators on the front panel which provide general information
about the equipment :
A status LED shows that the equipment is on.
A line hold LED indicates that a telephone line is seized and connected.
Additionally there are independent LED bar graph displays of 10 elements each
showing the relative levels of both the received and transmitted signals. The presence of signals within
the normal zone up to the maximum level before limiting takes place is an indication of normal
operation. The Rx and Tx bar graphs can be used to set the Rx and Tx gains using test tones.
The LED displays are driven by Q15 and Q16 controlled from the DSP Q20 data bus
outputs and have law shaping elements controlled within the DSP software.
There are also three LEDs mounted directly on the circuit board which provide
information about the transmit and receive signals and status information :
The LD1 Status LED indicates any error conditions at switch on by means of a flash
code :
Number of Flashes Error
3 Q18 error.
4 Q19 Test 1 error.
5 Q19 Test 2 error.
6 Q36 Codec IRQ error.
The flashing stops after approximately one minute and then begins a high speed
read/write of the device in question. If any of these errors should occur, please contact your nearest
Sonifex distributor.
LD2, the transmit LED, and LD3, the receive LED, are on whenever transmitting
and receiving respectively.