Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
RFL VF-6I RFL Electronics Inc.
December 15, 2011 20 (973)
334-3100
TRANSMIT SECTION
An analog voice input signal is fed into the VF-6I module through the rear backplane connections
which then goes to a balanced input transformer. The transformer output goes to an amplifier stage,
and then passes through the transmit attenuator. The switches (SW5) allow attenuation settings from
zero to 24.0 dB in 0.1 dB increments. The factory setting is +3 dB of attenuation for a -16 dBm input.
The attenuator output then passes through a testpoint to the μ-law PCM CODEC where the analog
voice is converted into an 8-bit, 64-Kbps digital signal. The maximum level at the testpoint is 5 Vp-p;
above this clipping occurs. The digitized audio signal then goes to the Logic Array where it is
processed before being transmitted to the proper timeslot. The equipment input jack in front of the
card is used for injection of a test tone.
The RFL VF-6I offers a choice of one of two signaling inputs at the backplane: SIGCON (signal
control) and M-LEAD.
SIGCON is compatible with the RFL VF-6. This input is pulled to +5V through a 4.7 K Ohm resistor.
This signal goes directly into the Logic Array and is multiplexed into the transmitted data. When this
input is grounded externally, the remote VF-6I is signaled and the local M Led is activated (BUSY).
When this circuit is open, the signal is IDLE.
M-LEAD is compatible with RFL VF-5A. M-LEAD is used when E&M Signaling Types I, II, or III
are desired. The M lead detector responds to an IDLE or BUSY signal from the external device. A
level of -48 volts at the M-LEAD indicates BUSY. Open or grounded indicates IDLE. The output of
M-LEAD goes into the Logic Array and is multiplexed in the TXDATA. The remote VF-6I is
signaled and the local M Led is activated. The PTC Resettable Fuse protects the VF-6I Module if the
MB-LEAD is accidentally shorted to ground.
RECEIVE SECTION
The VF-6I receives an 8-bit, 64-Kbps digital signal via the backplane from the appropriate timeslot.
The input signals go to the Logic Array where it is processed and de-multiplexed. The 8-bit digital
output of the Logic Array is then converted to an analog audio signal by the μ-law PCM CODEC and
is passed to the receive attenuator. The switches (SW4) allow attenuation settings from zero to 24.0
dB in 0.1 dB increments. The factory setting is +3 dB of attenuation for a +7 dBm output. The
attenuator output passes to an amplifier, and through the balanced output transformer to the rear
backplane connections. The equipment output jack on the front of the board allows retrieval of a test
tone.
The signaling portion of the received data from the Logic Array goes to the opto-coupler. Signaling is
active (BUSY) when E-LEAD is low. Signaling is inactive (IDLE) when E-LEAD is high. When
active in E&M Type I format, ground is BUSY and open is IDLE. In Type II or III, J1 is removed and
EB-LEAD is used. The VF-6I must have J1 removed if to be used as a direct replacement of an RFL
VF-6 module.
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