All Field Phones

These notes apply to all field telephones. There is more specific information for each type of phone, but this is the stuff you really need to know about. More generic communications notes are at https://comms.n3pb.org/.

Testing

TL;DR: Test everything you can before you go underground.

The general ideas apply to a radio or any other equipment you are going to use.

1. Inspect for obvious damage or missing parts.
2. Check phone configuration.
   • The TP-6N phones have no configurable options.
   • The TA-312 and TA-43 phones must be set for LB (local battery) and the ringer volume should be turned up the whole way.
   • The ringer volume on a TA-1 should be set to full.
3. Install batteries.
   • All of our phones are designed for D cells, but we use adapters to use AA cells.
   • With the TP-6N, three cells are inserted from the back of the phone with the positive terminal toward the front of the phone. There will be three AA to D adapters or one custom adapter for three AA cells in the phone.
   • With the TA-312 or TA-43, batteries go in one down and one up. It does not matter which goes where.
   • The TA-1 does not use batteries.
4. Check for sidetone.
   • Press the PTT button and talk into the transmitter. You should hear yourself in the receiver.
   • If this doesn't work, the most likely problem is the battery. Cells may be installed backwards or be dead.
   • If you have sidetone, jiggle wires and shake the phone a bit while you are talking to make sure nothing is loose.
   • This probably doesn't work with a TA-1. (???)
5. Test with another phone.
   • All of our phones are equipped with a cable that connects to the phone and has two SAE (trailer) connectors.
   • There may also be a SAE connector to alligator clip adapter attached to the cable. This can be used to connect to things that do not have connectors. Note that it is a common mistake to connect to the adapter rather than the two connectors on the cable from the phone.
   • From each phone
     • Ring the other phone.
     • Press the PTT and talk between the phones. Note that the phones are full-duplex, i.e. you can keep the PTT pressed while you talk and listen.
     • As above, jiggle wires around to make sure all connections are solid.
6. Test with the reel of cable you are going to use.
   • Our cable reels generally have SAE connectors on both ends. Just plug a phone into each end and test as above.
   • The most common problem is breaks where the connector is attached to the field wire.

Running the Wire

• Command will assign the locations where phones need to be available. The most common locations are at the entrance, underground branch director (underground coordinator), and at the patient.
• Phone wire should be run in places where it is not likely to be damaged by rescuers or in their way.
• Be sure rescuers are aware that following the phone line is not necessarily the best route to the patient. Frequently, the phone wire will be run in places that should are not on the easiest path so it is out of the way for other responders.
• The phones we use do not depend on wire polarity. So long as there is continuity of two wires, the phones will work.
• The phones are wired in parallel. All of them can talk to all of the other phones.
• If the phone wire must be run in a place that could provide a hazard or is likely to be damaged, attach flagging to make sure the line is visible.

Operations

• operations

Demobilization

• demobilization

Other Important Items

• If you find something damaged or broken, please label it and make sure it is reported so it can be fixed or removed from service.
• We prefer to use the TP-6N telephones. All of the phones mentioned here should work with each other.
• The field wire we use has four tinned-copper and three galvanized steel strands. The steel strands will ruin most wire strippers or cutters. Use the diagonal cutters provided in the tool kit (guitar string cutters) to cut the wire. Do not cut the wire with the strippers.
• Verify things are working if you have not used the phone in a while. It is a good idea to call another station every 10-20 minutes to verify that everything is still working.

Terms

sidetone

- hearing yourself talking into the transmitter when you listen to the receiver.

PTT (push to talk)

• most field phones require pressing a button on the handset to transmit.
• Note that the TP-6N is originally wired so the PTT buton must also be pressed to listen. Most TP-6N phones used for cave rescue have been modified so you can listen without pressing the button.
• You can still listen while the PTT is pressed.

LB (local battery)

- Talk battery is supplied by the phone. This is the most common situation for field phones used for rescue.

CB (common battery)

- Talk battery is supplied over the phone wires. This situation is not likely in most rescues and only applies if there is a central switchboard.

Training Standards

BVRS TRTQ

Blacksburg Volunteer Rescue Squad covers basic field phone operation in the TRTQ (Technical Rescue Trainee Qualified) class.

• Location of phones and wire on the cave rescue trailer.
• Hands-on experience with testing and deploying phones.
• Practical exercise involving message passing over phones and radios.

NCRC

The National Cave Rescue Commission includes field phone communications in several of their courses.

Note: Snapshots of the Communications Skills Check-off are provided below, but the NCRC thinks they are Super-Secret Squirrels and do not publish the current standards or most of their other training materials. YMMV

Orientation To Cave Rescue (OCR)

- No comms?

Level 1 - Task Force Member

Level 2 - Task Force Leader

• Advanced (all must apply)
  • Systematically identifies issue
  • Corrects issue in ≤3 attempts
  • Reestablishes working connection in ≤2 attempts.
  • Tests phone to confirm connectivity.
• Proficient (if any apply)
  • Randomly discovers issue
  • Multiple (>3) attempts to correct
• Needs Improvement (if any apply)
  • Unable to identify issue.
  • Unable to correct issue.
  • Does not conduct test to confirm connectivity.
  • Not per NCRC requirements. - super-secret and unpublished.

Level 3 - Vertical Specialist

- No comms?

Team Operations and Field Exercises (TOFE)

- No comms?

Small Party Assisted Rescue (SPAR)

- No comms?

---

Part of N3PB.org Phil Benchoff benchoff at n3pb.org