Y RECURSOS NATURALES
PARA OCUPAR ESOS 27 LUGARES
Two digital voice frequency service channels are available when the internal orderwire unit is used by itself. The number is reduced to one when a DVS II is also equipped, since the DVS II uses the data channel normally used by VF1.
The voice frequency signals are converted to bit streams (digitized) by a continuously variable slope delta (CVSD) modulator in the muldex unit. The digital service channel information is conveyed by overhead bits inserted and extracted by the muldex unit, which includes the voice frequency codecs and data interfaces.
NOTE
The handset, DTMF decoder, and speaker function with voice frequency channel #1 only.
Data channels
Two RS-232C (V.24) data channels are available to transmit low- speed data through the digital service channels by over sampling the data. The maximum bit rate of this low-speed data is limited to 10% of the sampling rate. Thus the maximum data rate for data channel 1 is 12.3 kb/s and the maximum data rate for data channelQuadralink Medium Capacity Radio THEORY OF OPERATION
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Signaling
The optional internal orderwire unit also provides a signaling facility. A dual-tone, multiple-frequency (DTMF) handset is used with voice frequency channel #1 to dial the address of a site. A three digit number is assigned to each site for selective signaling. Dialing between two successive digits must be completed within three seconds, otherwise that dialing sequence will be aborted. Multiple dialing is also possible. For example, by dialing the number 014131220, sites 014, 131, and 220 will be dialled (signaled). There should be a delay of at least four seconds between dialing the last digit of one site and the first digit of the next site.All sites in the system can be signaled simultaneously by depressing the ALL CALL button (*) on the handset keypad. When this button is depressed, a signaling tone is transmitted to all other sites along the radio route, to alert personnel that voice communication is required. Similarly, pressing the general call cancel button (#) on the handset cancels any signaling in progress at all sites in the system.
When a site is called, a tone warbles between 450 Hz and 550 Hz at the rate of approximately seven Hertz, and the E-lead relay is energized. The ringing stops and the E-lead relay de-energizes as soon as the handset is lifted off-hook; otherwise, the tone
continues for strap-selected intervals of 4, 8, or 32 seconds.
6.
The internal DVS Q
™service channel unit
(SD-099980)
The optional internal DVS Q™service channel unit provides up to
two digital voice frequency (VF) service channels and up to two RS-232C (V.24) / RS-422 (V.11) data channels that can be used
with the radio. The DVS Q™ service channel has two four way
digital bridges for the voice frequency signals, and two data bridges that permit two way repeater configurations to be accommodated without additional equipment.
Dual digital service channels are provided by codec and data interface circuitry within the muldex.
Selective signalling is possible by using a dual-tone,
multifrequency (DTMF) handset with the DVS Q™ service
channel unit. The handset is modified, and cannot be used
elsewhere. Other handsets will not function with the Quadralink®
Service channel functions
The optional DVS Q™ service channel unit performs the following functions when equipped:1. Interfaces the customer voice frequency and RS-232C (V.24) / RS-422 (V.11) signals with the muldex.
2. Provides the handset port with DTMF handset for selective signalling.
3. Provides a processor-controlled DTMF decode and warble generator (ringer).
4. Provides a speaker as well as an external speaker port. 5. Provides an 'ALL CALL' facility on the handset. 6. Provides a front panel hook-switch for the handset, or
optionally allows the handset to be cradled nearby (on a support that operates the handset hook-switch).
7. Provides a control to adjust the speaker and handset volume. 8. Provides a dry-contact relay output for customer signalling
of an incoming call.
9. Provides a dry-contact relay output for customer signalling of voice frequency channel failure.
10. Provides a remote control input to signal all the other
DVS Q™ units in the network of an incomming call.
11. Provides digital bypass for quiet multi-hop communications on large networks. Digital bridge add / drop facilities are
built in. Only when a handset is off-hook, does the DVS Q™
bridge the voice channel onto the network service channel. This results in the minimum number of analog to digital to analog voice conversions in multi-hop systems for clear communications with reduced voice channel noise. See figure 3-12.
Digital voice frequency (VF)
service channels
Two digital voice frequency service channels are available when
the internal DVS Q™ service channel unit is equipped.
The voice frequency signals are converted to bit streams (digitized) by a pulse code modulated (PCM) codec in the
DVS Q™ unit. The digital service channel information is
transmitted through the network by overhead bits inserted and extracted by the muldex.
Quadralink Medium Capacity Radio THEORY OF OPERATION
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Internal DVS Q™VF signal levels The signal levels for each voice frequency channel at the customer
access ports are shown in table 3-2.
The impedance of all inputs and outputs is 600 ohms. The voice frequency bridges perform the function of forwarding an input signal at any leg of the bridge to all other legs of the bridge except that at which the signal originated. See figure 3-11.
Figure 3-11: Voice bridge
NOTE
The handset, DTMF decoder, and speaker function with voice frequency channel #1 only.
Table 3-2: VF IN/OUT and VF IN/OUT AUXILIARY level selection
Port Input level Output level
VF1/2 -16 dBm 7 dBm 0 dBm 0 dBm VF1/2AUX -3.5 dBm -3.5 dBm 0 dBm 0 dBm LOCAL VF WEST VF EAST VF AUX VF LOCAL VF WEST VF EAST VF AUX VF LOCAL VF WEST VF EAST VF AUX VF LOCAL VF WEST VF EAST VF AUX VF
Data channels
Two RS-232C (V.24) / RS-422 (V.11) data channels are available to transmit low-speed data by the digital service channels by over sampling the data. The maximum bit rate of this low-speed data is limited to 10% of the sampling rate. Thus the maximum data rate for data channel 1 is 12.3 kb/s and the maximum data rate for data channel 2 is 6.1 kb/s. These data channels are multiplexed together with the digital service channels (voice channels) and the high- speed tributary data in the muldex.Internal DVS Q™ data channel
interface standards
The four way RS-232C (V.24) / RS-422 (V.11) data bridge accesses the following ports:
a. Data to / from RS-232C (V.24) / RS-422 (V.11)
b. RS-422 (V.11) to / from East (internal)
c. RS-422 (V.11) to / from West (internal)
d. RS-422 (V.11) to / from Aux
The data bridge also performs the bridging function of transferring the data at any input to all ports except that at which the data originated.
Signaling
The optional internal DVS Q™service channel unit also provides a signaling facility. A dual-tone, multiple-frequency (DTMF) handset is used with voice frequency (VF) channel #1 to dial the address of a site. A three digit number is assigned to each site for selective signaling. Dialing between two successive digits must be completed within three seconds, otherwise that dialing sequence will be aborted.Multiple dialing is also possible. For example, by dialing the number 014131220, sites 014, 131, and 220 will be dialled (signaled). There should be a delay of at least four seconds between dialing the last digit of one site and the first digit of the next site.
All sites in the system can be signaled simultaneously by depressing the ALL CALL button (*) on the handset keypad. When this button is depressed, a signaling tone is transmitted to all other sites along the radio route, to alert personnel that voice communication is required. Similarly, pressing the all call cancel button (#) on the handset cancels any signaling in progress at all sites in the system.
When a site is called, a tone warbles between 450 Hz and 550 Hz at the rate of approximately seven Hertz, and the E-lead relay is energized. The ringing stops and the E-lead relay de-energizes as soon as the handset is lifted off-hook; otherwise, the tone
Quadralink Medium Capacity Radio THEORY OF OPERATION
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A voice channel can be set off-hook by anyone of the following conditions:
• handset off hook,
• FSK input (VF2 channel only when in the FSK mode) and
• the auxiliary off hook inputs.