vhfBridge User Manual

Functional elements

Casing elements

1. Screws securing the casing lid. Unscrew with a bundled hexagon key (Ø 4 mm).
2. Space for a 12 V⎓ backup battery.
   

   Battery not included with vhfBridge set.

3. QR code with the device ID. It is used to pair the device with the Ajax security system.
4. Perforated part of the casing. Necessary for tamper triggering in case of any attempt to detach the device from the surface.
5. Perforated parts of the casing for cable output.
   

   The presence of the casing depends on the vhfBridge package. The device is supplied in two configurations: with a casing and without it.

vhfBridge board elements

1. Terminals for connecting a 12 V⎓ backup battery.
2. 100–240 V~ power supply input.
3. Tamper button. Signals if vhfBridge casing lid is removed.
4. Power button.
5. LED indicator.
6. QR code with the device ID. It is used to pair the device with the Ajax security system.
7. Terminals for connecting a VHF transmitter.

vhfBridge terminals

• BATT — input for the 12 V⎓ backup power connection.
• OUT — power output for the 12 V⎓ VHF transmitter (maximum output current is 2 A).
• OUT 1…8 — vhfBridge outputs for connecting a VHF transmitter.

LED indication

vhfBridge LED indicator may light up white, red, or green, depending on the status of the device.

Please note that the LED indicator is not visible when the casing lid is closed. The LED indicator is used at the stage of vhfBridge connecting and configuring. Later on, the state of the device can be monitored in the Ajax app.

LED indication of output status

Operating principle

vhfBridge is designed to connect third-party VHF transmitters to create an additional channel for transmitting events to the CMS.

The communication channel with the CMS created using vhfBridge can be used as the only or as a backup channel for communicating with the CMS (recommended more reliable option). This means that the hub can simultaneously transmit all events and alarms to the monitoring station of the security company not only through SIA (DC-09), ADEMCO 685, SurGard (Contact ID), and other proprietary protocols but also using vhfBridge.

The transponder receives information about alarms and events from the hub via the Jeweller radio channel. Then, vhfBridge transmits it to a third-party VHF transmitter via wires. The VHF transmitter, in turn, transmits all events and alarms to the CMS via a radio channel.

Events can be transmitted to the CMS via the Internet and vhfBridge in parallel. Transmission via the Internet works as the main channel because of greater reliability and informativity. The transmitted events may contain the zone number of the triggered detector, group number, user number, and other data. 

vhfBridge works as a backup communication channel duplicating all events transmitted via the Internet. The delivery speed of events and alarms in both cases does not exceed 1 second. 

An example of the algorithm of actions in case of an alarm from a MotionProtect motion detector:

1. MotionProtect has detected an alarm.
2. MotionProtect transmits the alarm to the hub via the Jeweller radio protocol.
3. The hub receives the MotionProtect alarm and transmits it to vhfBridge via the Jeweller radio protocol. 
4. vhfBridge receives the alarm from the hub and transmits it to the VHF transmitter over a wired connection.
5. The VHF transmitter receives the alarm and transmits it to the radio receiver on the CMS side via the radio channel. 
6. The radio receiver receives the alarm and transmits it to the CMS software.
7. The CMS receives and processes the alarm.

Output types

vhfBridge has 8 potential outputs for connection to a VHF transmitter. There are two types of outputs: 

1. High potential output (positive trip). 
2. Low potential output (negative trip).

The high-potential output does not supply voltage in the normal state. As soon as an alarm or event occurs, the output supplies a voltage of 12–14 V⎓. The low-potential output works the other way around. In the normal state, the voltage is maintained at 12–14 V⎓, and when an alarm or event occurs, it drops to 0 V.

The vhfBridge output type and alarm pulse duration are configurable in Ajax apps.

VHF transmitter power supply

vhfBridge can supply a third-party VHF transmitter with 12 V⎓ power (maximum output current is 2 A).

If the VHF transmitter has a current consumption of more than 2 A, it can be powered by the vhfBridge battery. In this case, disable battery charge tracking in the vhfBridge settings so that the system users do not receive notifications about the vhfBridge battery charging too long.

Sending events to the Central Monitoring Station (CMS)

The Ajax security system can transmit alarms to the PRO Desktop monitoring app as well as the Central Monitoring Station (CMS) using SurGard (Contact ID), SIA DC-09 (ADM-CID), ADEMCO 685, and other proprietary protocols. The list of supported protocols is available here.

When an alarm is received, the monitoring station operator of the security company knows what happened and where the rapid response unit has to be sent. All Ajax devices are addressable, so events, the device type, its assigned name and room can be transmitted to the PRO Desktop and the CMS. The list of transmitted parameters may differ depending on the type of the CMS and the selected communication protocol.

You can find vhfBridge ID and zone number in the States in Ajax apps. The device number corresponds to the loop (zone) number.

Adding to the system

vhfBridge doesn’t work with Hub, ocBridge Plus, uartBridge and third-party security central units. The device can only be added and configured through the Ajax PRO app by a user with administrator rights.

Before adding a device

1. Install the Ajax PRO app. Create an account. Add a hub to the app and create at least one virtual room. 
2. Check that the hub is on and has access to the Internet:via Ethernet cable, Wi-Fi, and/or mobile network. You can do this in the Ajax app or by checking the hub logo on the faceplate. It should light up white or green if the hub is connected to the network.
3. Check the status of the hub in the Ajax app and make sure that it is disarmed and does not start updates.

Only one vhfBridge module can be connected to one compatible Ajax hub.

To connect vhfBridge

1. Open the Ajax app. If your account has access to multiple hubs, select the one to which you want to add vhfBridge.
2. Go to the Devices menu and click Add Device.
3. Name the transponder, scan or enter the QR code manually (located on the device casing and packaging), and select a room and a group (if the group mode is activated).
4. Click Add — the countdown will begin.
5. Switch on vhfBridge by holding the power button for 3 seconds. Keep in mind that the hub connection request is only sent when the integration module is turning on.

Please note that to find and pair the device, the transponder should be located within the hub’s radio communication range (on the same secured premises).

If the connection has failed, disconnect vhfBridge for 5 seconds and try again. If the transponder has already been assigned to another hub, turn off vhfBridge and then follow the standard addition procedure.

The connected transponder will appear in the list of hub devices in the app. Device status updates depend on Jeweller settings. The default status update period in the app is 36 seconds.

Malfunction counter

When a vhfBridge malfunction is detected (e.g., no external power), the Ajax app will display a red icon with a number in the upper left corner of the device icon. This number indicates the number of malfunctions.

All malfunctions can be seen in the transponder states. Fields with malfunctions will be highlighted in red.

Icons

Icons display some of the vhfBridge states. You can check them in the Ajax app in the Devices tab.

Icon	Meaning
	Jeweller Signal Strength. Displays the signal strength between the hub and vhfBridge. Recommended value is 2–3 bars.
	The charge level of the battery connected to vhfBridge.
	Displays when vhfBridge is operating via a radio signal range extender.
	vhfBridge is temporarily disabled. Learn more
	vhfBridge tamper triggering events are temporarily disabled. Learn more

States

States can be found in the Ajax app:

1. Go to the Devices tab.
2. Select vhfBridge from the list.

vhfBridge settings

Settings can be changed in the Ajax app:

1. Go to the Devices tab.
2. Select vhfBridge from the list.
3. Go to Settings by clicking the icon in the upper right corner.
4. Set the parameters.
5. Click Back to save the new settings.

Please note that after editing the settings, you should click the Back button to save them.

vhfBridge output configuration

By default, vhfBridge outputs are configured as follows:

• 1st output — intrusion
• 2nd output — panic button
• 3rd output — malfunction
• 4th output — tamper
• 5th output — loss of vhfBridge power supply
• 6th output — power loss of the hub
• 7th output — hub battery discharged
• 8th output — loss of communication between the hub and vhfBridge

The settings of outputs can be changed in the Ajax app:

1. Go to the Devices tab.
2. Find vhfBridge in the list of devices.
3. Go to the Outputs menu.
4. Find the output in the list and go to its Settings by clicking the gear icon .
5. Set the parameters.
6. Click Back to save the new settings.

Event types of vhfBridge outputs

Icon	Type of event	Operating mode	Description
	Not assigned	No	Output disabled.
	Intrusion	Pulse	Alarm when motion, opening, and other detectors are triggered.
	Fire	Pulse	Alarm when fire detectors are triggered.
	Medical help	Pulse	Alarm when pressing the call button for medical help.
	Panic button	Pulse	Alarm by clicking: DoubleButton Button in panic button mode The panic button on the SpaceControl key fob The panic button connected to the Transmitter or MultiTransmitter The functional button of Ajax keypads when it operates in panic button mode The virtual panic button in Ajax apps
	Any alarm	Pulse	Alarm of any connected detector.
	Malfunction	Pulse	Any malfunction of the connected detectors.
	Transponder external power failure	Bistable	Loss of external 110–240 V~ power supply to vhfBridge transponder.
	Transponder battery low	Bistable	vhfBridge backup battery is discharged.
	Hub external power failure	Bistable	Loss of external 110–240 V~ power supply to the hub.
	Hub battery low	Bistable	Hub backup battery is discharged.
	Lid	Pulse	Triggering of tamper of any device in the system.
	Security mode change	Bistable	Changing the security mode of an object or group.
	Confirmed intrusion alarm	Pulse	Confirmed alarm according to PD 6662:2017.
	Confirmed hold-up alarm	Pulse	Confirmed hold-up device alarm according to PD 6662:2017.
	Hub-transponder connection loss	Bistable	Loss of vhfBridge connection with the hub / radio signal range extender via Jeweller channel.

The time before sending an event regarding the loss of communication between the hub and vhfBridge to the CMS is calculated with the following formula:

“Hub — detector” polling interval × 30 undelivered packets.

With the minimum values of the “hub — detector” polling interval, an event regarding the loss of communication with the hub is sent to the CMS in 6 minutes.

Connecting VHF transmitter to vhfBridge

List of recommended VHF transmitters

• Hawk VHF Alarm Transmitter (FSK Electronics)
• TX750C (RDC)
• TR-41 (Puper)

vhfBridge can be connected to any VHF transmitter with relay inputs. Connection via UART, RS-485, and other interfaces is not supported.

How to connect a VHF transmitter to vhfBridge

When connecting the VHF transmitter, do not twist the wires together, but solder them. The ends of the VHF transmitter wires, which will be inserted into the vhfBridge terminals should be tinned or crimped with a special sleeve.

1. Turn off the vhfBridge power (if power was connected).
2. Turn off vhfBridge.
3. Select vhfBridge outputs to which you want to connect the VHF transmitter.
4. Pull the VHF transmitter wires into the vhfBridge casing through the holes.
   

   There are perforated sections on the casing that can be broken off so that the cable could be pulled through them.

5. Connect the VHF transmitter to the control outputs of vhfBridge according to the wiring diagram in the User Guide supplied by the VHF transmitter manufacturer.
6. Fasten the cable securely to the vhfBridge terminals using a straight screwdriver (slot PL 3.0).
7. Connect the power to the VHF transmitter.
   

   If a VHF transmitter requires 12 V power to operate, it can be connected to the power terminals of the corresponding vhfBridge zone. Do not connect the external power supply to the transmitter power terminals, as this may damage the device.

8. Connect power to vhfBridge.
9. Turn on vhfBridge.

vhfBridge functionality testing

Integration module functionality tests do not start immediately but not later than over a single “hub — detector” polling interval (36 seconds with standard hub settings). You can change the polling period of devices in the Jeweller menu of the hub settings.

Tests are available in the device settings menu:

1. Sign in to the Ajax app.
2. Go to the Devices menu .
3. Select vhfBridge.
4. Go to Settings by clicking on the gear icon .

Available tests:

• Jeweller Signal Strength Test

Selecting vhfBridge placement

The placement of vhfBridge determines its distance from the hub and the presence of obstacles between them that impede the passage of the radio signal: walls, inter-floor constructions, or large-sized objects located in the room.

Be sure to check the signal strength at the installation site. If the signal strength is low (a single bar), we cannot guarantee a stable operation of the security system. At the very least, relocate the device as repositioning even by 20 cm can significantly improve signal reception.

If poor or unstable signal strength is still reported after the relocation of the device, use the radio signal range extender.

When choosing the installation location, consider the distance between vhfBridge and the VHF transmitter: the cable length should be sufficient for connection.

The minimum distance between vhfBridge and the radio transmitter is 2 meters and the maximum distance is 7 meters. The minimum distance is required to avoid signal overlapping. The maximum distance allowed will help avoid signal attenuation in the cable.

Material and cross-section of the cable for connecting a VHF transmitter are determined by the manufacturer’s requirements and the maximum current. All requirements can be found in the manual or from the customer service of the VHF transmitter manufacturer.

vhfBridge installation

Prior to mounting vhfBridge, ensure that you have selected the optimal location corresponding to these instructions.

The transponder casing should be mounted on a vertical surface. If installed on a horizontal surface, the tamper will not work when somebody attempts to dismantle the transponder.

To install vhfBridge:

1. Remove the vhfBridge casing lid by unscrewing the bottom and top screws with the bundled hex wrench.

   

2. Remove the vhfBridge board from the holders by pulling them to the sides.

   

3. Prepare cable openings in advance by carefully breaking out the perforated parts of the casing.

   

4. Fasten the casing to a vertical surface at the chosen installation location using the bundled screws. When attaching, use all the fixation points on the casing. One of them, in the perforated part of the mount above the tamper, is needed to trigger the tamper on the back of the board in case of an attempt to tear the casing off the surface.
   

   

5. Run the cables into the transponder casing through the previously made holes.
6. Install the vhfBridge board into the casing on the racks.

   

7. Connect VHF transmitter to vhfBridge. Follow the polarity and connection order of the wires. Securely fasten the conductors to the terminals.
8. Secure the cable with cable ties using special mounts inside the casing.

   

9. Install a 12 V⎓ backup battery on the special holders in the casing. Please note that vhfBridge cannot be connected to third-party power supply units.
   

   We recommend using a 12 V⎓ battery of 4 or 7 Ah. For such batteries, special holders in the casing are designed. You can also use similar batteries of a different capacity, of the matching size, and with a charging time of no more than 30 hours. The maximum dimensions of the battery to be installed in the casing are 150 × 65 × 94 mm, and the weight is 5 kg.

10. Connect a backup battery to the board terminals according to the wiring diagram below (use the bundled cable). Follow the polarity and connection order of the wires. Securely fasten the conductors to the terminals.

    

11. Connect 100–240 V~ external power supply.
12. Add an integration module to the system.
13. Install the lid on the casing and fix it with the bundled screws.
14. Test vhfBridge and connected VHF transmitter.

Do not install vhfBridge

• Outdoors. Doing so may cause the device to malfunction or not work properly.
• Near metal objects or mirrors (for example, in a metal cabinet). They can shield and attenuate the radio signal.
• Inside premises with temperature and humidity outside the permissible limits. Doing so may cause the device to malfunction or not work properly.
• At a distance less than 1 meter from the hub or range extender. This could result in the loss of connection with the hub.
• At a distance less than 2 meters from the VHF transmitter. The minimum distance is required to avoid signal overlapping
• At a distance more than 7 meters from the VHF transmitter. The maximum distance allowed will help avoid signal attenuation in the cable.

Maintenance

Check the functionality of vhfBridge regularly. The optimal frequency of checks is once every three months. Clean the casing from dust, cobwebs, and other contaminants as they emerge. Use a soft dry cloth suitable for equipment care. Do not use any substances containing alcohol, acetone, gasoline, and other active solvents to clean the device.

Technical Specifications

Complete set

1. vhfBridge.
2. Power cable.
3. 12 V battery connection cable.
4. Installation kit.
5. Casing (depends on configuration).
6. Quick Start Guide.

Warranty

Warranty for the Limited Liability Company “Ajax Systems Manufacturing” products is valid for 2 years after the purchase.

If the device does not work correctly, you should first contact the support service. In most cases, technical issues can be resolved remotely.

Contact Technical Support:

• e-mail
• Telegram