Jam

local modem = peripheral.find("modem", function(name, obj) return obj.isWireless() end)
if not modem then
    error("No wireless modem detected", 0)
end
local close = false
if not modem.isOpen(gps.CHANNEL_GPS) then
    modem.open(gps.CHANNEL_GPS)
    close = true
end

while true do
    local e, _, recvChannel, sendChannel, msg = os.pullEventRaw()
    if e == "modem_message" and recvChannel == gps.CHANNEL_GPS and msg == "PING" then
        modem.transmit(sendChannel, gps.CHANNEL_GPS, {{}, {}, {}})
        print("Jam ID: " .. (tostring(sendChannel) or "[ERR]"))
    elseif e == "terminate" then
        if close then
            modem.close(gps.CHANNEL_GPS)
        end
        return
    end
end