SPECIFICATIONS - Simulcast Automatic Delay Lines

SPECIFICATIONS - Simulcast Automatic Delay LineSystem

Delay Lines operating on baseband voice frequencies are used in simulcast radio systems to match the time delay of transmission paths to prevent garbled reception in areas where multiple transmitters "overlap". Automatic delay modules at each site shall dynamically delay all frequencies by a variable time factor to compensate for varying transmission delay. Products provided shall be Models ADL and CTU as manufactured by Convex Corp. of Sterling, VA, or pre-approved equivalent. Based on the system design of __ sites and __ channels, and with consideration to spares, __ ADL-12 and __ CTU-12 shall be provided.

The delay line shall operate on voice frequencies, provide a wide range of delay adjustment, polarity correction, and 12 dB of amplitude adjustment. Automatic Delay Lines shall be installed at all base station sites. LAN or touch-tone (DTMF) control shall provide a means of setting delay lines. A “DTMF” Indicator shall be provided on the front panel as a diagnostic tool. This LED shall light when valid touch-tones are detected. Valid touch-tone commands will be acknowledged with a tone burst output.

An accurate 1PPS input permit the automatic delay line to be “time synchronized” to Coordinated Universal Time (UTC). The 1PPS shall be supplied by a Master Oscillator that is synchronized to UTC via GPS.

The LAN Port can be assigned a unique IP address by the user. They shall be shipped with a default IP address. Since these devices can also be controlled by touch-tones and multiple ADL’s serve the same radio channel, DTMF addressing is used. This permits each delay line to be controlled individually. Each ADL can be user set to respond to a unique two-digit address. Up to 98 units can be individually controlled from a CTU. Once set, the ADL’s can be made “deaf” to further touch-tones with the security feature. A security feature shall disable touch-tone control so that delay lines can not be altered by random touch-tones. Security can be applied to individual delay lines or to all delay lines simultaneously.

Automatic delay lines require a corresponding controller located at the “head end”. Channel Timing Units are used in simulcast radio networks to control Automatic Delay Lines. A CTU is required for each simulcast channel to provide timing test signals so that the automatic delay lines can measure the “talk out” time delay to each transmit site. ADL’s use the delay measurement to automatically deploy and maintain the appropriate total “hold delay” and polarity for each simulcast site.

One Channel Timing Unit is deployed at the central control point on a per channel basis to generate timing test signals. When the channel is idle the controller sends test signals to all delay lines on the channel. The delay lines measure Link Delay and make any needed adjustments. When the channel is keyed for transmission the controller shuts down the test signal and passes voice through to the delay lines. The delay lines hold their last bulk delay and polarity setting during voice transmission.

When Push To Talk (PTT) or tone keying is asserted, test signals are removed and voice is through to the talk out links.

Coordinated Universal Time (UTC) synchronization enables the CTU / ADL’s to precisely measure the time delay of talk out links. Both the CTU and the ADL’s have a 1 Pulse Per Second (1 PPS ) Input that is synchronized to UTC.

PTT keying shall be provided. Where PTT control is not feasible, the CTU will detect tone keying for purposes of controlling the test signals. Tone keying is passed through to the ADL’s at the transmitter sites. ADL’s are normally set to pass tone keying through to the base stations. In the event that base stations require DC keying, ADL’s can be set to: detect tone keying, provide a PTT contact closure, and remove the guard tone.

Automatic delay lines measure Link Delay and makes Bulk Delay adjustments required to maintain a fixed total Hold Delay. It also measures the polarity of the timing signal and automatically maintains consistent polarity for voice traffic.

Both the CTU and ADL’s are synchronized to Coordinated Universal Time (UTC) by their 1 PPS Inputs. At the control point, the test signal provided by the CTU has an embedded timing mark that is transmitted through the audio link. At transmitter sites, ADL’s receive the test signal and use digital signal processing (DSP) to measure the time delay and polarity of the “talk out” link. The time is the Link Delay in microseconds. The polarity is determined to be normal or inverted from the polarity of the Channel Timing Unit.

Deviation of individual transmitters can be adjusted using the FLAT GAIN amplifier in the ADL’s. ADL Flat Gain is adjustable and can be remotely controlled by the LAN Port or touch-tones from the central control point.

A two-piece connector with screw locks will be provided for signal and power wires. An AC to 12 VDC Adapter shall be provided.

Automatic Delay Line SPECIFICATIONS

Frequency Range4 Hz to 3400 Hz

Output Impedance600 ohm - balanced, floating

Bulk Delay Range300 to 700,000 microseconds in 1 microsecond steps

Delay Measurement0 to 700,000 microseconds, 1 microsecond resolution

Polarity ControlNormal or Inverted selection

Gain Range- 6 dB to +6 dB, 0.1 dB steps

1PPS InputUTC (Coordinated Universal Time),

1 Pulse Per Second Input

Input Z: >1.5K Ohm / TTL Logic

Time mark: Low to Hi transition

Minimum pulse width: 1 uSec.

LAN PortEthernet 10 Base-T, Control via Telnet Session (Windows Hyperterminal)

Link / Activity LEDs

Simple Menu displays status of all parameters.

Touch-Tone ControlAddressable: 00 to 98

Detector Range-26 to -6 dBm

On / Off Time100 mSec minimum

DTMF LEDON = valid Touch-Tone

DTMF Security8 Character sequences

Controller SPECIFICATIONS

PTT InputHigh Impedance / Bridging Input

Input Z: 100K Ohm / TTL or E/M

M Type I,II,III: Key <-20 V / Idle >-20 V

M Type IV, V; E: Key >-20 V / Idle <-20 V

TTL: Key < +2.5 V / Idle > +2.5 V

TTL Inv.: Key > +2.5 V / Idle < +2.5 V

PTT SwitchNormal: PTT asserted - passes voice

Idle: PTT not active - applies Test Signal

Tone KeyingDetected for Test Unit control, Passed through for far end PTT control

General SPECIFICATIONS

Environmental-30° to +60°C, 0 to 95% R.H.

Power Input-12: 10 - 18 VDC / 250 mA max Options:-24: 19 – 36, or -48: 37 - 72 VDC

Dimensions1.7" H x 4.25" W x 9.4" D (4.3 cm x 10.8 cm x 23.9

MountingWall mount or rack mount. DLP-19 for rack mount

WarrantyOne year, starting at date of shipment.