Difference between revisions of "DNVT"

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Digital Nonsecure Voice Terminals (DNVTs) are digital field telephones using a 4-wire interface with signaling at 16kbps or 32kbps. Each wire pair carries data in one direction, i.e. one pair of binding posts at each end is a transmit output, and the other is a receive input. The devices may be powered over the 4-wire interface (common battery mode), or may be locally powered (local battery mode) when used in pairs without a telephone exchange. Not all DNVTs support local battery mode mode.
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[[File:TA-1042A-Top.jpg|thumb|alt=TA-1042A/U DNVT|TA-1042A/U DNVT]] The Digital Nonsecure Voice Terminal (DNVT) is a telephone set which transmits and receives conditioned diphase modulated data at a signaling rate of 16 or 32 kilobits per second (kbps) over a 4-wire interface.<ref>FM 3-04.120 &para;2-83.</ref> It is available in either desk set or field telephone models<ref name="Kirsch1609">Kirsch 1981, p. 1609.</ref> Field models include:
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Tactical DNVTs include:
 
  
 
* [[TA-954/TT]]
 
* [[TA-954/TT]]
 
* [[TA-1035/U]]
 
* [[TA-1035/U]]
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* [[TA-1042A/U]]
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* [[TA-1042A/U]] (with data connector for AN/UXC-7 tactical facsimile machine, AN/UGC-144 communications terminal, etc.)<ref>FM 3-04.120 &para;2-84.</ref>
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Pairs of [[TA-1042A/U]] DNVTs may be used in local battery (LB) mode as simple field phones, without requiring connection to a telephone exchange. The [[TA-954/TT]], however, must always be connected to a telephone exchange as it does not support direct DNVT-to-DNVT connection. When the [[TA-1042A/U]] is operated in local battery mode, a power source of 24-56 VDC must be connected to the PWR binding posts on the right side of the phone, with positive voltage connected to the red post.
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When connected to a telephone exchange and configured in common battery (CB) mode, the DNVT receives 24-56 VDC phantom power from the telephone exchange over the send/receive line pairs.<ref name="Kirsch1609" /> Positive voltage is applied to either or both of the red RCV terminals, and negative voltage is applied to either or both of the black XMT terminals.
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''(TBD: Can the [[TA-1035/U]] be operated without connection to an exchange? Can either the [[TA-954/TT]] or [[TA-1035/U]] be powered in LB mode?)''
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The DNVT offers the following features:<ref>FM 3-04.120 &para;2-85.</ref>
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* Digital telephone/data set for mobile subscriber equipment (MSE) and TRI-TAC systems.
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* Full duplex voice or data communications.
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* Push-to-talk (PTT) for combat radio net interface.
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* Standard four-wire loop interface.
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* Mean time between failures (MTBF): 150,000 hours.
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* Automatic tracking of 16 or 32 kbps switch loop rate via autobaud feature.
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The DNVT has the following specifications:<ref name="Kirsch1609" /><ref>FM 3-04.120 &para;2-86.</ref>
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* Data rates of 16 or 32 kbps synchronous or up to 2400 bits per second asynchronous. ''(TBD: Does this only apply to the [[TA-1042A/U]]?)''
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* Loop interface: four-wire line, up to 4km of [[WF-16/U]] field wire.
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* Line impedance: 125&Omega; &plusmn;10% resistive.
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* Operating voltage: 24 to 56 volts DC.
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* Audio codec: [[Wikipedia:Continuously_variable_slope_delta_modulation|continuously variable slope delta modulation]].
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* Signal format: Conditioned diphase at 16 or 32 kbps.
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* Codeword format: Cyclically permuted 8-bit words.
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* Output level: 3V peak to peak.
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* Input level: between 150 mV and 4V peak to peak.
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== Related Files ==
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;{{pdf|TTC-39.pdf|TTC-39 TRI-TAC family brochure from GTE Sylvania}}
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== Notes ==
  
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DNVTs are intended to be connected to telephone exchanges (and in some cases, to each other) with [[WF-16/U]] two-pair field telephone wire. DNVTs are compatible with digital telephone exchanges such as the [[media:TTC-39.pdf|AN/TTC-39 TRI-TAC family]].
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<references />
  
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Signaling and operating states are paritally documented in IEEE Transactions on Communications, Vol. COM-29, No. 11, November 1981, pages 1609 through 1614:
 
  
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:[http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=1094902 The Digital Nonsecure Voice Terminal]
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== References ==
  
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The above article is available for purchase, but is not included here due to copyright restrictions. The article provides considerable insight into the DNVT signaling, but does not provide sufficient details to implement compatible hardware. An effort is underway to attempt to reverse-engineer the DNVT signaling and produce an open specification, as part of the [[DNVT2IP]] project.
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* Kirsch, Alan L. ''et. al.'' (November 1981). "The Digital Nonsecure Voice Terminal", ''IEEE Transactions on Communications'', Vol. COM-29, No. 11, pp. 1609-1614. ([http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=1094902 link])
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* Headquarters, Department of the Army (February 2007). "Air Traffic Services Operations", ''Field Manual FM 3-04.120 (FM 1-120)''. ([[media:FM3-04-120.pdf|link]])
  
 
[[Category:Military/Field Phones]]
 
[[Category:Military/Field Phones]]

Latest revision as of 00:18, 12 September 2013

TA-1042A/U DNVT
TA-1042A/U DNVT

The Digital Nonsecure Voice Terminal (DNVT) is a telephone set which transmits and receives conditioned diphase modulated data at a signaling rate of 16 or 32 kilobits per second (kbps) over a 4-wire interface.[1] It is available in either desk set or field telephone models[2] Field models include:


Pairs of TA-1042A/U DNVTs may be used in local battery (LB) mode as simple field phones, without requiring connection to a telephone exchange. The TA-954/TT, however, must always be connected to a telephone exchange as it does not support direct DNVT-to-DNVT connection. When the TA-1042A/U is operated in local battery mode, a power source of 24-56 VDC must be connected to the PWR binding posts on the right side of the phone, with positive voltage connected to the red post.

When connected to a telephone exchange and configured in common battery (CB) mode, the DNVT receives 24-56 VDC phantom power from the telephone exchange over the send/receive line pairs.[2] Positive voltage is applied to either or both of the red RCV terminals, and negative voltage is applied to either or both of the black XMT terminals.

(TBD: Can the TA-1035/U be operated without connection to an exchange? Can either the TA-954/TT or TA-1035/U be powered in LB mode?)


The DNVT offers the following features:[4]

  • Digital telephone/data set for mobile subscriber equipment (MSE) and TRI-TAC systems.
  • Full duplex voice or data communications.
  • Push-to-talk (PTT) for combat radio net interface.
  • Standard four-wire loop interface.
  • Mean time between failures (MTBF): 150,000 hours.
  • Automatic tracking of 16 or 32 kbps switch loop rate via autobaud feature.


The DNVT has the following specifications:[2][5]

  • Data rates of 16 or 32 kbps synchronous or up to 2400 bits per second asynchronous. (TBD: Does this only apply to the TA-1042A/U?)
  • Loop interface: four-wire line, up to 4km of WF-16/U field wire.
  • Line impedance: 125Ω ±10% resistive.
  • Operating voltage: 24 to 56 volts DC.
  • Audio codec: continuously variable slope delta modulation.
  • Signal format: Conditioned diphase at 16 or 32 kbps.
  • Codeword format: Cyclically permuted 8-bit words.
  • Output level: 3V peak to peak.
  • Input level: between 150 mV and 4V peak to peak.


Related Files

Adobe PDF icon.png TTC-39 TRI-TAC family brochure from GTE Sylvania


Notes

  1. ↑ FM 3-04.120 ¶2-83.
  2. ↑ 2.0 2.1 2.2 Kirsch 1981, p. 1609.
  3. ↑ FM 3-04.120 ¶2-84.
  4. ↑ FM 3-04.120 ¶2-85.
  5. ↑ FM 3-04.120 ¶2-86.


References

  • Kirsch, Alan L. et. al. (November 1981). "The Digital Nonsecure Voice Terminal", IEEE Transactions on Communications, Vol. COM-29, No. 11, pp. 1609-1614. (link)
  • Headquarters, Department of the Army (February 2007). "Air Traffic Services Operations", Field Manual FM 3-04.120 (FM 1-120). (link)
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