Method and receiving unit for synchronizing a packet-oriented reception with a calculated tone signal

Patent metadata

Field	Value
Publication number	US-9456089-B2
Application number	US-74766708-A
Country	US
Kind code	B2
Filing date	Dec 8, 2008
Priority date	Dec 19, 2007
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

In addition to the transmission of a tone signal (ts) according to the RFC standard 2833 via a network using Internet protocol, the tone signal is transmitted in the data packets (dp). Subsequently, the phase difference (Δφ) between the transmitted tone signal (ts) and the generated tone signal (ts′) is ascertained, before beginning the insertion of the generated tone signal (ts′) in the data packets (dp), and compared to a predetermined phase difference (φν). If the ascertained phase difference exceeds the predetermined phase difference (Δφ,φν), the phase of the generated tone signal (ts′) is changed by a predetermined phase (φ) with the aid of the tone generator (TG). The ascertainment of the phase differences (Δφ) and the change of the phase (φ) of the generated tone signal (ts′) is repeated until the ascertained phase difference is less than the predetermined phase difference (Δφ,φν), upon which instead of the transmitted tone signal (ts), the generated tone signal (ts) is inserted into the data packets (dp). A substantial advantage of the invention can be seen in that a phase detector does not have to be continuously active for the synchronization, but rather the synchronization must only be performed if a tone signal (ts) or tone information (ti) is received and the insertion of the generated tone signal (ts′) is imminent.

First claim

The invention claimed is:

1. A method for synchronizing a tone signal transmitted in data packets comprising:
a) inserting a tone signal into transmitted data packets wherein the tone signal is transmitted by tone-signal specific information in the data packets;
b) generating a tone signal according to the transmitted tone information using a tone generator;
c) ascertaining a phase difference between the transmitted tone signal and the generated tone signal before insertion of the generated tone signal into the data packets begins and comparing the ascertained phase difference to a predefined phase difference;
d) upon a determination that the ascertained phase difference exceeds the predefined phase difference changing the phase of the generated tone signal by the tone generator to a predefined phase; and
e) repeating steps c) and d) until the ascertained phase difference lies under the predefined phase difference then inserting the generated tone signal into the data packets in place of the transmitted tone signal.

2. The method of claim 1 , comprising:
f) storing a last two transmitted bit patterns of the transmitted tone signal that were produced before a predefined insertion time of the generated tone signal into the data packets; and
g) ascertaining a last stored bit phase difference between a last stored bit pattern and a last bit pattern for the generated tone signal produced before the insertion time;
h) ascertaining a previously stored bit pattern phase difference between the previously stored bit pattern and the previous bit pattern for the generated tone signal produced before the insertion time;
i) comparing the last stored bit phase difference and the previously stored bit pattern phase difference with the predefined phase difference;
j) upon a determination that the last stored bit phase difference and the previously stored bit pattern phase difference exceed the predefined phase difference shifting a phase of the generated tone signal by a predefined phase value using the tone generator; and
k) repeating steps f) through j) until at least one of the last stored bit phase difference and the previously stored bit pattern phase difference lies below the predefined phase difference.

3. The method of claim 2 , wherein the comparing of the last stored bit phase difference and the previously stored bit pattern phase difference occurs prior to a comparison of other bit phase differences.

4. The method of claim 1 , comprising producing and transmitting the transmitted tone information according to Request for Comments (RFC) standard 2833.

5. The method of claim 1 , comprising producing and transmitting the data packets with the Real-Time Transport Protocol (RTP) according to Request for Comments (RFC) standard 3511.

6. The method of claim 1 , wherein the transmitted tone signal is a fax signal or a modem signal.

7. Receiving equipment for synchronizing a tone signal transmitted in data packets comprising:
a) a receiving unit for receiving a transmitted tone signal inserted in data packets and for receiving a piece of tone-signal specific tone information transmitted in the data packets;
b) a tone generator for generating a generated tone signal produced according to said tone information and having a phase;
c) a phase detector for ascertaining a phase difference between the transmitted tone signal and the generated tone signal before insertion of the generated tone signal into the data packets begins, and for comparison with a predefined phase difference;
wherein the tone generator is configured such that, upon a determination that an ascertained phase difference exceeds the predefined phase difference the phase of the generated tone signal is shifted by a predefined phase; and
wherein the receiving equipment is configured such that ascertaining the phase difference and configuring the tone generator to shift the generated tone signal by the predefined phase are repeated until the ascertained phase difference lies under the predefined phase difference, the generated tone signal being inserted in the data packets in place of the transmitted tone signal upon the ascertain phase difference being under the predefined phase difference.

8. The receiving equipment of claim 7 , wherein the ascertained phase difference is a first ascertained phase difference and the receiving equipment further comprising:
d) an insertion/reading unit and a memory for storing a last two transmitted bit patterns of the transmitted tone signal that were produced before a preset insertion time for inserting the generated tone signal in the data packets
e) a phase detector for ascertaining a second phase difference between a last stored bit pattern and a last bit pattern produced from the generated tone signal before the insertion time, and
for ascertaining a third phase difference between a previous stored bit pattern and a previous bit pattern produced before the insertion time, and
for comparing the ascertained second and third phase differences with the predefined phase difference; and

wherein the tone generator is configured such that, if the ascertained second and third phase differences exceed the predefined phase difference, the phase of the generated tone signal is shifted by a predefined phase value; and
wherein the insertion/reading unit, the memory, the phase detector, and the tone generator are configured such that ascertainment of the second and third phase differences and shifting of the phase of the generated tone signal are repeated until the ascertained second phase difference or the ascertained third phase difference lies under the predefined phase difference.

9. Receiving equipment of claim 8 , wherein the piece of tone-signal specific tone information is generated according to RFC standard 2833 is received.

Assignees

• Fabian Thomas
• Bauer Wolfgang
• Unify Gmbh & Co Kg

Inventors

• Fabian Thomas
• Bauer Wolfgang

Classifications

• H04N1/00217

  only involving computer data transmission protocols, e.g. SMTP, WAP or HTTP (communication protocol aspects and techniques in packet data networks H04L69/00; network-specific arrangements or communication protocols supporting networked applications H04L67/00) · CPC title

• H04N2201/0015

  Control of image communication with the connected apparatus, e.g. signalling capability · CPC title

• H04N1/00214

  details of transmission · CPC title

• H04M7/1295 Primary

  Details of dual tone multiple frequency signalling · CPC title

• H04L65/608

  Electricity · mapped topic