ROCKY MOUNTAIN VHF SOCIETY - TECHNICAL INFORMATION


REPEATERS' STATUS (10/13/2012):

146.76 repeater system - transmitter and all receive sites operating normally

224.02 repeater system - operating normally

449.55 repeater - operating normally (repaired 11/09. See picture on right).  

220/440 link - operating normally

 

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NBP displaying defective legacy component from UHF transmitter.


 

RMVHFS 146.76 REPEATER

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Gunbarrel Transmit/Local Receive Site

Louisville Remote Receiver Site

The 146.16/146.76 MHz WIA repeater is the designated emergency repeater for Boulder County. See the BCARES WEB-SITE for information on the services performed and for membership information.

The '76 2-meter amateur repeater is a sophisticated multi-site system based on commercial 2-way radio equipment with some additional custom designed hardware. The primary repeater is a Motorola MSR-2000 rated for 100 watts continuous output. Multiple receive sites and a network of microwave and UHF links provide for coverage from hand held radios throughout the plains and mountain areas of Boulder County. The receive sites and UHF links utilize General Electric Mastr-II equipment. The GE four channel voting comparator is located at the Gunbarrel site. Power at the Gunbarrel site is fully backed up with generator equipment.

100 Hz sub-audio tone (PL, CG, or CTCSS) is required to access the receivers. See note below*.

The PRIMARY TRANSMIT SITE is located on Gunbarrel Hill in northeast Boulder County located approximately at an elevation of 5415' MSL. Published coordinates of this repeater is 40.0628N, 105.1506W  datum WGS85 -  UTM Zone 13, N 4434527, E 487156.

The antenna at Gunbarrel has 6-dB gain for transmit and receive and is set for an omni-directional pattern. It is fed with low-loss semi-rigid feed line.  The roughly 300 watt ERP signal is adequate to provide usable reception at virtually all locations on the plains and in the mountains of Boulder County

Three additional receive sites are located within the County to provide for coverage from hand-held 2-meter radios. A receiver in the hills above the town of Lyons provides for good coverage in the northern part of the Boulder mountains. Another receive site is located on the Davidson Mesa. A fourth receiver is in the Table Mesa area on Shanahan Ridge to cover the South area of the county. The four receivers provide for excellent receive coverage in mountain valleys and for improved reception for mobiles due to diversity reception that helps eliminate mobile flutter effects. A voting system ensures that the best receive signal is repeated on a continuous and instantaneously switched basis. The received signals are linked to the transmit site via a network of digital microwave and analog UHF one-way links. All links and the transmit site can be controlled by the authorized control operators in-band and via a number of additional access points. A carefully engineered arrangement of reverse-burst and inhibit tone encoders on the UHF links assures minimal switching delays between receivers and the virtual elimination of transmitted double squelch bursts. This unique system was designed and implemented by NBP.

The courtesy beep utilizes a system of tones to identify the receive site in use after the end of each received transmission as follows:

RECEIVE LOCATION

BEEP

PITCH

TONE REQUIRED

Gunbarrel

Single beep

Medium

100 Hz (see Note below)

Louisville

Single beep

Low

100 Hz

Lyons

double beep

high followed by medium

100 Hz

Table Mesa

double beep

high followed by low

100 Hz

The ID, DE WIA/R T*, is transmitted via modulated CW every 5 minutes. (MCW ID's on the UHF links are transmitted every 9 minutes but are not retransmitted by the VHF repeater output.) The repeater time out timer (to prevent a permanent key up condition) is 2 minutes and is reset whenever the input signal is dropped long enough to allow the "courtesy beep" to be heard. The transmit hang time is 4 seconds. The transmitted 100 Hz tone is eliminated during the hang time in order to minimize squelch burst noise being received by the users who have activated their transceiver's tone decoding, and to facilitate cross-band mobile extender operation. 

If no courtesy beep is transmitted, this is an indication that the voting system has been temporarily disabled and reception is only via the Gunbarrel local receiver. Likewise, if the "T" suffix is not heard on the ID then the Gunbarrel receiver is operating carrier squelch. See notes below for more details. 


*NOTE REGARDING CTCSS TONES

Repeater Transmit:

The 146.76 repeater transmitter superimposes a 100 Hz sub audible (CTCSS, PL, or CG) tone on all transmissions. A tone decoder is not required by users to hear the transmit signal, but if used will eliminate local RF interference and squelch burst noise. 

Repeater Receive:

Although the 146.76 repeater system remains an open repeater system for all users, a 100 Hz sub audible tone is required to access the system. This requirement is not intended to restrict access, but to minimize the effects of any RF interference generated near the multiple receive sites. This requirement can be temporarily removed by a control operator if necessary.

The repeater's transmit WIA/R modulated tone identification includes an additional "dash" (Morse "T" for TONE) to indicate that the local Gunbarrel receiver is in the tone receive mode.

Temporary Suspension of tone requirement on Gunbarrel Receiver:

The requirement for tone access at the local Gunbarrel receive site can be defeated by any user by their transmitting a DTMF (touch-tone) "". For the following approximately 5 minutes the main Gunbarrel receiver will operate without the receive tone requirement. The 5 minute timer is restarted whenever a tone is received on any of the receivers. Note that in order for this temporary defeat to occur, the tone must be transmitted from a station already implementing the 100 Hz subaudible tone. In addition, the tone requirement can be disabled from the Gunbarrel receiver for any length of time by the control operators.

RMVHFS 2-METER REPEATER SYSTEM

 

 

 

RMVHFS 449.55/224.02 REPEATER SYSTEM

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449.55/224.02 Linked Repeater Site at Lee Hill

7903' MSL + tower 40.0722N, 105.3539W  -  UTM Zone 13, N 4435620, E 469822

Inputs at 222.42 and 444.55 MHz are usually repeated/translated simultaneously to 224.02 and 449.55 MHz. The 70 cm machine transmits a continuous 100 Hz tone and normally requires a 100 Hz (PL, CG, or CTCSS) tone to key up. A CTCSS tone decoder is not required by users to hear the 70 cm transmit signal, but if used will eliminate local RF interference and squelch burst noise. The 222.42 MHz input is carrier squelch. Both inputs are open to all users. Linking and other functions are controllable by the authorized control operators via a number of gateways, and some limited linking to the 2-meter repeater is possible for emergency situations.

These two repeaters (449.55 and 224.02 MHz ) are normally accessible through the EchoLink internet linking system. Call sign: W0IA-R. Node: 217336. For more information about EchoLink, follow this link: EchoLink.