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+ +

MTS & IMTS

+ +
+ + + +

+ +History +

+ +

+From Wikipedia, the free encyclopedia: +

+"The Improved Mobile Telephone Service (IMTS) was a pre-cellular VHF/UHF radio system which linked to the PSTN. +IMTS was the radiotelephone equivalent of land dial phone service. +Introduced in 1964, it replaced Mobile Telephone Service (MTS) and improved on most MTS systems by offering direct-dial rather than connections through a live operator." +

+ +

+MTS and IMTS phone were assembled in large cases located in the trunk of cars. +Early models used mechanical switches to encode and decode phone's identity. +Later models were solid state and had duplexers to talk and listen simultaneously. +Attaché case phones came available in the late 60's, so they could be used outside the car. +Some models in the 80's were handheld. +

+ +
+ +

+

    +
  • Frequency range VHF Low: 35.26 - 35.66 MHz (down-link); 43.26 - 43.66 MHz (up-link) +
  • Frequency range VHF High: 152.48 - 152.84 MHz (down-link); 157.74 - 158.10 MHz (up-link) +
  • Frequency range UHF: 454.375 - 454.65 MHz (down-link); 459.375 - 359.65 MHz (up-link) +
  • 10 channels used for VHF Low Band in the US +
  • 11 channels used for VHF High Band in the US +
  • 13 channels used for VHF High Band in Canada +
  • 12 channels used for UHF Band in the US +
  • Duplex distance: around 5 MHz (VHF High and UHF) +
  • Channel spacing: 30 KHz (VHF High) 25 KHz (UHF) +
  • Modulation: FM +
  • Frequency deviation: 5 KHz (signaling tones) +
  • Mobile station transmit power: Typically 25 Watts +
  • Base station transmit power: 100..250 Watts +
+

+ +

+ +How IMTS works +

+ +

+This description is not an original standard. +It is based on my research. +There are many unknown parameters. +If you know more, please help to complete this documentation. +

+ +

+Frequencies: +

+ +

+ + + + + + + + + + + + + +
VHF Low Band
ChannelBase (MHz)Mobile (MHz)
ZO35.2643.26
ZF35.3043.30
ZM35.3843.38
ZH35.3443.34
ZA35.4243.32
ZY35.4643.46
ZR35.5043.50
ZB35.5443.54
ZW35.6243.62
ZL35.6643.66
+ + + + + + + + + + + + + + + + +
VHF High Band
ChannelBase (MHz)Mobile (MHz)
JJ152.48157.74 (Canada only)
JL152.51157.77
YL152.54157.80
JP152.57157.83
YP152.60157.86
YJ152.63157.89
YK152.66157.92
JS152.69157.95
YS152.72157.98
YR152.75158.01
JK152.78158.04
JR152.81158.07
JW152.84158.10 (Canada only)
+ + + + + + + + + + + + + + + +
UHF Band
ChannelBase (MHz)Mobile (MHz)
QC454.375459.375
QJ454.40459.40
QD454.425459.425
QA454.45459.45
QE454.475459.475
QP454.50459.50
QK454.525459.525
QB454.55459.55
QO454.575459.575
QR454.60459.60
QY454.625459.625
QF454.65459.65
+

+ +

+The modulation is FM. The frequency deviation of speech is 2500 Hz ??? at 1000 Hz. +Signaling tones have a frequency deviation of 5000 Hz. +Pre-Emphasis is used for speech only. +

+ +

+Tones used for signaling: +

+ +

+ + + + +
Base -> Mobile
Idle2000 Hz
Seize1800 Hz
+

+ +

+ + + + + +
Mobile -> Base
Guard2150 Hz
Connect1633 Hz
Disconnect1336 Hz
+

+ +

+Idle State: +

+ +

+All transceivers of a base station that are not in use, are turned off, except for one channel, the idle channel. +Only one channel being idle will transmit the 2000 Hz Idle tone and listens for the 2150 Hz Guard tone. +If the (only) channel with the Idle tone is seized by a mobile phone or the public telephone exchange, another channel, that is turned off, is activated and sends the Idle tone and becomes the new idle channel. +

+ +

+When a mobile phone is idle, it will search for a radio channel with Idle tone and suitable quality. +The transmitter will be off while the phone listens to the Idle tone or an incoming call from the base station. +When the Idle tone disappears for about 250 ms ???, it will search for another idle channel. +

+ +

+Call from mobile phone: +

+ +

+When the user picks up the handset of the mobile phone, the phone will seize the channel, transmits ANI and receives dial tone. +

+ +

+First, the mobile phone will turn on the transmitter and sends 350 ms of 2150 Hz Guard tone, followed by 50 ms of 1633 Hz Connect tone. +As soon as the Guard tone, followed by Connect tone is detected by the base station, it will turn off 2000 Hz Idle tone and transmit silence. +(Another channel that is turned off, will then transmit the 2000 Hz Idle tone.) +Note that the base station has to respond even before the 50 ms of the Connect tone is over. +The mobile phone must detect the silence from the base station before it is done sending the Connect tone. +(There are special requirements on SDR/soundcard setup to respond fast enough.) +The mobile phone then continues to send Guard tone and waits for the base station to respond with the 1800 Hz Seize tone. +Note that there seems to be no timeout in the mobile phone, waiting for Seize tone. +The base station sends 250 ms of the Seize tone. +

+ +

+If the mobile phone receives the Seize tone, it will send the ANI sequence. +The ANI sequence consists of 190 ms of Guard tone, followed by 7 pulsed digits. +Each digit is formed by pulses consisting of 25 ms Mark tone and 25 ms of Space tone. +After the last pulse of each digit the mobile phone sends 190 ms of Space tone. +The Mark tone is transmitted as 1633 Hz Connect tone. +The Space tone is transmitted as silence, if the pulse number was odd. +The Space tone is transmitted as 2150 Hz Guard tone, if the pulse number was even. +The pulse number is counted from the first pulse of the first digit through the last pulse of the last digit. +The mobile phone will then through-connect speech path, the user awaits the dial tone. +

+ +

+The base station verifies the received ANI and presents a dial tone or forwards the call to an operator. +

+ +

+When a number is dialed from a mobile phone, Guard tone is sent continuously as soon a the dial goes off normal (when the dial is moved from its resting position), which should be about 400 ms ???. +Each digit is formed by pulses consisting of 60 ms Mark tone and 40 ms of Space tone. +The Mark tone is transmitted as 1633 Hz Connect tone. +The Space tone is transmitted as 2150 Hz Guard tone. +The Space tone continues until the dial returned to normal, which should be about 200 ms ???. +

+ +

+Call towards mobile phone: +

+ +

+The land user dials the phone number of the mobile phone. +It consists of the 3 digit area code and the 4 digit suffix. +The 3 digit prefix (mobile exchange) is omitted when paging the mobile phone. +

+ +

+First, the base station selects the idle channel that is transmitting the 2000 Hz Idle tone. +(Another channel that is turned off, will then transmit the 2000 Hz Idle tone.) +If there is no channel available, the land user receives a busy signal. +The 7 digit number is transmitted towards the mobile phone via alternating tones. +The base station transmits a 1800 Hz Seize tone for about 400 ms (???) before, between and after each digit. +Each digit is formed by pulses consisting of 50 ms Mark tone and 50 ms of Space tone. +The Mark tone is transmitted as 2000 Hz Idle tone. +The Space tone is transmitted as 1800 Hz Seize tone. +The base station will start timer for 3 to 4 seconds waiting for the mobile phone to respond with a 2150 Hz Guard tone. +

+ +

+If the mobile phone receives digits from base station, it compares the digits with its own number. +If the number does not match, it will abort and scan for the idle channel. +If the number matches the mobile phone will transmit the Guard tone up to 750 ms, waiting for the ringing sequence. +After sending Guard tone, the mobile phone will ring and wait for answer. +

+ +

+If the base station does not receive the Guard tone from the mobile phone, it will return to idle state. +The land user will receive an announcement that the called phone is not available at this moment. +If the base station receives the Guard tone from the mobile phone, it will send a ringing sequence for about 45 seconds. +Ringing by the base station is composed of 1800 Hz Seize tone and 2000 Hz Idle tone, each alternating after 25 ms for 2 seconds, then 4 seconds of Seize tone. +

+ +

+The mobile phone rings the bell using the tones received from the base station. +If the 1800 Hz Seize tone disappears, the phone stops ringing and returns to idle channel. +

+ +

+If the user of the mobile phone answers, the mobile phone transmits 1633 Hz Connect tone for 400 ms and through-connects speech path. +

+ +

+If the base station receives the Connect tone, it will stop the ringing sequence, answers the call from the land user and through-connect the speech path. +

+ + +

+Release by the mobile phone: +

+ +

+If the mobile user hangs up, the mobile phone starts the release sequence by sending alternating 1336 Hz Release tone and 2150 Hz Guard tone, 25 ms each. +After 750 ms sending that sequence, the mobile phone turns off transmitter and searches for idle channel. +

+ +

+When the base station receives the release sequence, it will return to idle state. +

+ + +

+Release by the base station: +

+ +

+When the mobile phone is ringing, it will stop if the base station removes the ringing sequence. +There is no release sequence to release an a active call towards mobile phone. +

+ +

+ +How MTS works +

+ +

+Base station in Idle state: +

+ +

+The base station uses a 600 Hz tone to indicate an idle channel. +Similarly to the IMTS, only one idle channel send the 600 Hz tone, the other channels are turned off. +

+ +

+Call from mobile phone +

+ +

+The mobile station does not send any signaling tone at all. +The radio signal is used to start a call. +Whenever the user picks up the phone and presses the push-to-talk button, a connection is made to an operator. +The operation is half duplex, so there is no release by stopping transmission of the mobile phone. +The operator has to terminate the call. +

+ +

+Call from base station +

+ +

+To page a mobile phone, the operator has to dial the 5 digits of the mobile phone. +The operator has to add the digit '1' in front of the 5 digit subscriber ID. +This digit is used to reset the paging detector inside mobile phone. +Note that the subscriber ID must not have a digit '1'. +Each pulse from the base station is a transition from 600 Hz to 1500 Hz or from 1500 Hz to 600 Hz. +Two or more pulses are separated 100 ms. +Each digit is separated 400 ms ???. +After the last pulse of the last digit, the tone sustains until the caller hangs up. +The mobile phone rings. +To answer the call, the user presses the push-to-talk button. +The ringing can be released by sending another transition pulse or by removing the tone for a short time. (This is for further study.) +

+ +

+ +Setup of an IMTS base station +

+ +

+Find out what band and channels your phone supports. Then get a list of all available bands and channels: +

+ +
+
+# src/imts/imts -k list
+
+
+ +

+Assume the phone supports VHF Low band, so we select channel 'YK' with the command line option '-k YK', or select any other channel your phone supports. +In order to have a low latency, you must add '-b 5' to the command line option. +Then tune the transmitter to the indicated channel and receiver to the other indicated channel. +Transmit with a normal loud speech volume, but not too loud. +The actual level is not yet relevant. +

+ +
+
+# src/imts/imts -k YK -b 5
+...
+imts.c:381 info   : Entering IDLE state on channel YK, sending 2000 Hz tone.
+imts.c:336 notice : Created channel #YK
+Base station on channel YK ready, please tune transmitter to 152.660 MHz and receiver to 157.920 MHz. (-5.260 MHz offset)
+on-hook: ....... (enter digits 0..9)
+
+
+ + +

+If you receive permanent buffer underruns, see 'Fast Seize' below. +Power on your phone. +Be sure to use attenuator on the antenna, so it will not transmit full 25 Watts close to your receiver equipment. +The phone should search and stop at the selected channel. +If the phone does not support automatic channel selection, select channel YK manually. +

+ +

+Now pick up the handset of your phone and it should transmit the Guard tone, followed by a short Connect tone. +If the phone does not lock or does not transmit, check if your transmitter transmits the Idle tone. +If the phone transmits, your base station should respond to the seize sequence by the phone and the phone transmits ANI towards your base station. +

+ +
+
+# src/imts/imts -k YK -b 5
+...
+imts.c:381 info   : Entering IDLE state on channel YK, sending 2000 Hz tone.
+imts.c:336 notice : Created channel #YK
+Base station on channel YK ready, please tune transmitter to 152.660 MHz and receiver to 157.920 MHz. (-5.260 MHz offset)
+imts.c:886 notice : Received Guard tone, turning off IDLE tone
+imts.c:544 info   : Received seize (Guard + Connect tone) from mobile phone.
+imts.c:545 info   :  -> Guard tone duration: 350 ms (level 69%)
+imts.c:408 info   : All channels are busy now, cannot activate any other channel.
+imts.c:907 notice : Sending Seize to mobile phone.
+imts.c:784 info   : Received ANI digit '2' from mobile phone (level 71%).
+imts.c:784 info   : Received ANI digit '1' from mobile phone (level 77%).
+imts.c:784 info   : Received ANI digit '6' from mobile phone (level 77%).
+imts.c:784 info   : Received ANI digit '2' from mobile phone (level 77%).
+imts.c:784 info   : Received ANI digit '6' from mobile phone (level 77%).
+imts.c:784 info   : Received ANI digit '3' from mobile phone (level 71%).
+imts.c:784 info   : Received ANI digit '0' from mobile phone (level 71%).
+imts.c:790 info   : ANI '2162630' complete, sending dial tone.
+
+
+ +

+If the base station does not receive Guard tone or receives bad ANI digits, check the receiver and the receive level. +To test the receiver side, tune the receiver to the frequency of the transmitter and check the loopback signal. Adjust your receiver (sound card input) to match about 100% level: +

+ +
+
+...
+imts.c:876 notice : Received idle tone (level of 97%), loopback?
+imts.c:876 notice : Received idle tone (level of 97%), loopback?
+imts.c:876 notice : Received idle tone (level of 97%), loopback?
+imts.c:876 notice : Received idle tone (level of 97%), loopback?
+...
+
+
+ +

+Return your receiver to the uplink frequency and try to make a call again. +If it works, use you dial pad (or rotary dial) to dial the number. +

+ +

+To call towards mobile station, enter the 7 digit mobile station ID on your keyboard or add it to the command line. +Use the same phone number you received with the ANI above, this is your mobile station ID. +Then press 'd' to page and ring the phone: +

+ +
+
+...
+mncc_console.c:358 info   : Outgoing call to '2162630'
+call.c:699 info   : Received MNCC call from fixed network '' to mobile '2162630'
+call.c:706 info   : Indicate MNCC call confirm towards fixed network
+call.c:717 info   : Outgoing call from '' to '2162630'
+imts.c:1176 info   : Call to mobile station, paging number: 2162630
+imts.c:445 info   : Entering paging state, sending phone's ID '2162630'.
+imts.c:408 info   : All channels are busy now, cannot activate any other channel.
+imts.c:942 info   : Sending paging digit '2' as pulses.
+imts.c:942 info   : Sending paging digit '1' as pulses.
+imts.c:942 info   : Sending paging digit '6' as pulses.
+imts.c:942 info   : Sending paging digit '2' as pulses.
+imts.c:942 info   : Sending paging digit '6' as pulses.
+imts.c:942 info   : Sending paging digit '3' as pulses.
+imts.c:942 info   : Sending paging digit '0' as pulses.
+imts.c:755 info   : Received acknowledge (Guard tone) from mobile phone (level 71%).
+call.c:440 info   : Call is alerting
+call.c:428 info   : Indicate MNCC alerting towards fixed network
+mncc_console.c:202 info   : Call alerting
+imts.c:466 info   : Received response from mobile phone, ringing.
+imts.c:1013 info   : Sending ringing signal as pulses.
+imts.c:1022 info   : Sending pause after ringing.
+imts.c:1013 info   : Sending ringing signal as pulses.
+imts.c:1022 info   : Sending pause after ringing.
+imts.c:763 info   : Received answer (Connect tone) from mobile phone (level 75%).
+call.c:478 info   : Call has been answered by '2162630'
+call.c:466 info   : Indicate MNCC answer towards fixed network
+mncc_console.c:206 info   : Call connected to '2162630'
+imts.c:476 info   : Received answer from mobile phone, conversation started.
+
+
+ +

+To disconnect a call, the phone must be hung up: +

+ +
+
+...
+imts.c:654 info   : Received disconnect sequence from mobile phone (level 90%).
+imts.c:418 info   : Turing transmitter off.
+imts.c:381 info   : Entering IDLE state on channel YK, sending 2000 Hz tone.
+
+
+ +

+Level adjustment: +

+ +

+Don't care about it, if you use SDR, since levels are always correctly modulated. +Now it is time to actually care about the correct transmit and received level. +In the example above you see a level around 70..77%. +Now tune your receiver to your transmitter frequency again. +Adjust the level to something around 73% using a variable resistor on my soundcard's input. (+- 10% is good) +

+ +
+
+...
+imts.c:876 notice : Received idle tone (level of 88%), loopback?
+imts.c:876 notice : Received idle tone (level of 76%), loopback?
+imts.c:876 notice : Received idle tone (level of 73%), loopback?
+imts.c:876 notice : Received idle tone (level of 73%), loopback?
+imts.c:876 notice : Received idle tone (level of 73%), loopback?
+imts.c:876 notice : Received idle tone (level of 73%), loopback?
+...
+
+
+ +

+Now, whatever frequency deviation the phone transmits for signaling, so does your base station. (Around 73% in this case.) +Use the other variable resistor (connecting your receiver) to adjust the volume until the level matches about 100%. (+- 10% is good) +Switch back the receiver to up-link frequency and see the result from your phone. (You should now receive the phone at around 100%.) +

+ +

+Pre- and De-Emphasis: +

+ +

+In order to have correct level of signaling tones, your transmitter and your receiver should not use pre- and de-emphasis. +Let this software do that instead, then the signaling tones do not use pre-emphasis, just the voice. +If possible, add command line option '-p' for pre-emphasis of the transmit signal and '-d' for de-ephasis of the received signal. +Don't care about it, if you use SDR, since pre-emphasis and de-emphasis is automatically selected and used. +

+ +

+Fast seize detection: +

+ +

+Sometimes your sound device might not be fast enough to handle a small sound buffer. +The maximum buffer of 5 ms (command line option '-b 5') might cause repeating trouble: +

+ +
+
+sound_alsa.c:458 error  : Buffer underrun: Please use higher latency and enable real time scheduling
+sound_alsa.c:127 error  : cannot prepare audio interface for use (Device or resource busy)
+sender.c:330 error  : Failed to get number of samples in buffer (rc = -32)!
+sender.c:338 error  : Trying to recover!
+
+
+ +

+ +We must not increase buffer, because we would detect the Connect tone too late, so we would respond too late. +We must respond before we detect the Connect tone, so that our response matches the time the Connect tone is actually transmitted by the phone. + +

+ +

+To do this we must measure the length of the Guard tone. +First pick up the phone and remember the Guard tone duration. +It should be close to 350 ms. +

+ +
+
+imts.c:544 info   : Received seize (Guard + Connect tone) from mobile phone.
+imts.c:545 info   :  -> Guard tone duration: 349 ms (level 99%)
+
+
+ +

+Now put the base station into loopback mode and tune receiver to transmitter or loop soundcard's output to input. +

+ +
+
+# src/imts/imts -k YK -l 2
+...
+imts.c:942 info   : Sending paging digit '1' as pulses.
+imts.c:861 info   : Received paging test digit '1' (level 103%  delay 68 ms).
+imts.c:942 info   : Sending paging digit '2' as pulses.
+imts.c:861 info   : Received paging test digit '2' (level 103%  delay 67 ms).
+imts.c:942 info   : Sending paging digit '3' as pulses.
+imts.c:861 info   : Received paging test digit '3' (level 103%  delay 67 ms).
+
+
+ +

+In this case the soundcard's round trip delay is 67 ms. +Substract 67 from 349 and you get 282. +Add '-F 282' to command line option, instead of '-b 5'. +Now we react about 282 ms after we detected the start of the Guard tone. +The reaction now matches the time when the phone transmits the Connect tone. +(Tested with a Limermore LAP-2000 phone.) +

+ +

+Detecting loss of carrier signal: +

+ +

+This works with SDR only, because we do not have any RSSI (Received Signal Strength Indicator) signal from a radio connected to the sound card. +With SDR we know the RX level, so we can define a threshold value for a lost signal. +Use '-S <db>' or '--squelch <db>' to define the squelch threshold level. +To measure the noise floor, use the 'm' key to get a bar graph of the current RSSI. (RF level) +Add some dB to the noise floor for the squelch threshold value. +An easier way is to use '-S auto' or '--squelch auto' to automatically measure the noise floor level and then automatically use a threshold level that is some dB above this measured level. +This level is then used to detect loss of carrier. +Also this level is used to mute the audio path, whenever the signal gets lost for a short time. +After about 12 seconds of signal loss, a call is released. +

+ +
+...
+squelch.c:94 info   : RF signal measurement: -69.2 dB noise floor, using threshold of -63.2 dB
+...
+
+ +

+In the following example I cut off the power of the phone being in a call and waited 12 seconds for the base station to time out: +

+ +
+...
+squelch.c:114 info   : RF signal weak: Muting audio (RF -77.6 dB < -70.7 db)
+imts.c:491 notice : Detected loss of signal after 12 seconds, releasing.
+...
+
+ +

+ +Setup of an MTS base station +

+ +

+To detect an outgoing call or answer from a mobile phone, it is required to use squelch. +Squelch is only available with SDR support. +The command line option '-M' is used to switch to MTS mode. +Also we use loopback mode '-l 2' to test RF loopback. +Alternatively use '-l 1' to perform an internal loopback. +The following example shows setup with LimeSDR (not LimeSDR mini!): +

+ +
+
+# src/imts/imts --limesdr -k JS -M -l 2
+...
+imts.c:443 info   : Entering paging test state, sending digits 1234567890.
+imts.c:408 info   : All channels are busy now, cannot activate any other channel.
+imts.c:336 notice : Created channel #JS
+Base station on channel JS ready, please tune transmitter to 152.690 MHz and receiver to 157.950 MHz. (-5.260 MHz offset)
+...
+imts.c:861 info   : Received paging test digit '1' (level 98%  delay 9139 ms).
+imts.c:992 info   : Sending paging digit '1' as pulses.
+imts.c:861 info   : Received paging test digit '1' (level 100%  delay 80 ms).
+imts.c:992 info   : Sending paging digit '2' as pulses.
+imts.c:861 info   : Received paging test digit '2' (level 100%  delay 78 ms).
+imts.c:992 info   : Sending paging digit '3' as pulses.
+imts.c:861 info   : Received paging test digit '3' (level 100%  delay 77 ms).
+imts.c:992 info   : Sending paging digit '4' as pulses.
+imts.c:861 info   : Received paging test digit '4' (level 100%  delay 78 ms).
+imts.c:992 info   : Sending paging digit '5' as pulses.
+imts.c:861 info   : Received paging test digit '5' (level 100%  delay 77 ms).
+imts.c:992 info   : Sending paging digit '6' as pulses.
+...
+
+
+ +

+Now run the base station without loopback. +Add "-S auto" to use squelch level with automatic level calibration. +Be sure to have an attenuator, so you do not saturate your input of your SDR. +Refer to the SDR help page for more information and input level display. +The following example shows a call from mobile phone, just by transmitting toward base station: +

+ +
+
+# src/imts/imts --limesdr -k JS -M -S auto
+...
+squelch.c:61 info   : RF signal squelch: Use automatic threshold
+imts.c:386 info   : Entering IDLE state on channel JS, sending 600 Hz tone.
+imts.c:336 notice : Created channel #JS
+Base station on channel JS ready, please tune transmitter to 152.690 MHz and receiver to 157.950 MHz. (-5.260 MHz offset)
+...
+dsp.c:466 info   : Low RF level, muting.
+squelch.c:99 info   : RF signal measurement: -69.9 dB noise floor, using squelch threshold of -59.9 dB
+squelch.c:99 info   : RF signal measurement: -70.2 dB noise floor, using squelch threshold of -60.2 dB
+squelch.c:112 info   : RF signal strong: Unmuting audio (RF -54.2 >= -60.2 dB)
+dsp.c:476 info   : High RF level, unmuting; turning transmitter on.
+imts.c:506 info   : Detectes RF signal in IDLE mode, calling the opterator at '010'.
+call.c:405 info   : Incoming call from 'unknown' to '010'
+call.c:407 info   :  -> Call to Operator '010'
+call.c:385 info   : Indicate MNCC setup towards fixed network
+mncc_console.c:165 info   : Incoming call from ''
+mncc_console.c:196 info   : Call automatically answered
+call.c:744 info   : Received MNCC answer from fixed network
+call.c:746 info   : Call answered
+call.c:748 info   : Indicate MNCC setup complete towards fixed network
+
+
+ +

+To terminate the call, press 'h': +

+ +
+
+mncc_console.c:388 info   : Call hangup
+call.c:774 info   : Received MNCC release from fixed network with cause 16
+call.c:778 info   : Call released toward mobile network
+imts.c:1237 info   : Call has been released by network, releasing call.
+imts.c:1254 notice : Outgoing release, during call, releasing!
+imts.c:418 info   : Turing transmitter off.
+imts.c:386 info   : Entering IDLE state on channel JS, sending 600 Hz tone.
+
+
+ +

+To call the mobile phone, enter the number as command line parameter or after running the base station. +Then press 'd' to dial the number. +If the phone rings, answer by start transmitting: +

+ +
+
+on-hook: 23042 (press d=dial)
+mncc_console.c:358 info   : Outgoing call to '23042'
+call.c:699 info   : Received MNCC call from fixed network '' to mobile '23042'
+call.c:706 info   : Indicate MNCC call confirm towards fixed network
+call.c:717 info   : Outgoing call from '' to '23042'
+imts.c:1177 info   : Call to mobile station, paging number: 23042
+imts.c:445 info   : Entering paging state, sending phone's ID '23042'.
+imts.c:408 info   : All channels are busy now, cannot activate any other channel.
+imts.c:992 info   : Sending paging digit '2' as pulses.
+imts.c:992 info   : Sending paging digit '3' as pulses.
+imts.c:992 info   : Sending paging digit '0' as pulses.
+imts.c:992 info   : Sending paging digit '4' as pulses.
+imts.c:992 info   : Sending paging digit '2' as pulses.
+imts.c:975 info   : Digits complete, assuming the phone is ringing.
+call.c:440 info   : Call is alerting
+call.c:428 info   : Indicate MNCC alerting towards fixed network
+mncc_console.c:202 info   : Call alerting
+...
+squelch.c:112 info   : RF signal strong: Unmuting audio (RF -66.5 &g6;= -67.7 dB)
+dsp.c:476 info   : High RF level, unmuting.
+imts.c:520 info   : Detected RF signal, mobile is now transmitting.
+call.c:478 info   : Call has been answered by '23042'
+call.c:466 info   : Indicate MNCC answer towards fixed network
+mncc_console.c:206 info   : Call connected to '23042'
+imts.c:476 info   : Received answer from mobile phone, conversation started.
+
+
+ +

+Use MTS with 7 digit ID or IMTS with 5 digit ID: +

+ +

+Some later phone allow to operate in IMTS and MTS networks. +In order to roam, the caller ID length can be different. +Use command line option '-5' to use IMTS mode with 5 digit IDs. +Use command line option '-7' to use MTS mode with 7 digit IDs. +

+ +
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+
+ + diff --git a/docs/imts.jpg b/docs/imts.jpg new file mode 100644 index 0000000..cd9db3e Binary files /dev/null and b/docs/imts.jpg differ diff --git a/docs/imts_small.jpg b/docs/imts_small.jpg new file mode 100644 index 0000000..dadccfc Binary files /dev/null and b/docs/imts_small.jpg differ diff --git a/docs/index.html b/docs/index.html index 568749b..90fde54 100644 --- a/docs/index.html +++ b/docs/index.html @@ -31,20 +31,20 @@ NMT (Nordic Mobile Telephone) + - + MTS / IMTS (USA / Canada) AMPS (USA) / TACS (UK / Ireland / Italy) - Transmit TV test image signals + - + Transmit TV test image signals my early radio setup - @@ -88,6 +88,7 @@ Implemented networks:
  • B-Netz (Germany) ATF-1 (Netherlands)
  • C-Netz (Germany)
  • NMT 450 / 900 - Nordic Mobile Telephone (Scandinavia)
  • +
  • MTS / IMTS - (Improved) Mobile Telephone Service (USA / Canada)
  • AMPS - Advanced Mobile Phone Service (USA)
  • TACS / JTACS - Total Access Communication System (UK/Italy/Japan)
  • Radiocom 2000 (France)
  • diff --git a/docs/style.css b/docs/style.css index 248c72d..06b6850 100644 --- a/docs/style.css +++ b/docs/style.css @@ -74,12 +74,21 @@ td { table.nmt { width: 400px; border-spacing: 0px; - border:4px solid black; - border-collapse:collapse; + border: 4px solid black; + border-collapse: collapse; } td.nmt { padding: 3px; - border:4px solid black + border: 4px solid black; +} + +table.imts { + width: 600px; + text-align: center; + table-layout: fixed; + border-spacing: 0px; + border: none; + border-collapse: collapse; } li {