T1 channel bank control process and apparatus

• US 5,740,241 A
• Filed: 05/12/1995
• Issued: 04/14/1998
• Est. Priority Date: 05/12/1995
• Status: Expired due to Term

• Current Assignee: Dell Marketing Corporation (Dell Technologies Inc.)
• Original Assignee: Carrier Access Corporation (Dell Technologies Inc.)
• Inventors: Clark, Phillip, Koenig, Roger L., Bullington, Thomas
• Primary Examiner(s): Zele, Krista M.
• Assistant Examiner(s): SAINT SURIN, JACQUES M
• Application Number:
  US08/440,099
• Time in Patent Office: 1,068 Days
• Field of Search: 379/413, 379/412, 379/399, 379/400, 379/324, 323/293, 323/270, 323/273
• US Class Current: 379/399.01
• CPC Class Codes: H04M 19/005 Feeding arrangements without the use of line transformers
• CPC Class Codes: H04M 19/02 providing ringing current or supervisory tones, e.g. dialling tone or busy tone
• CPC Class Codes: H04M 3/005 Interface circuits for subscriber lines current supply H04M19/00 and subgroups; supervisory, monitoring or testing arrangements H04M3/22 and subgroups; in key telephone systems H04M9/006
• CPC Class Codes: H04M 7/0096 Trunk circuits

Abstract

A technique for powering telephone lines using an unbalance current source and current sink; and a technique for improving attenuation/frequency distribution and return loss (impedance matching) of transformer-coupled wire-line communications circuits by using secondary series capacitance and an AC current pump signal source; and a generation of ringing voltage as positive voltage pulses with respect to a negative power supply voltage; and a technique for removal of AC power ripple by using an active linear floating filter for the purpose of powering telephone line circuits, and a technique for injection of real time tone samples into T1 transmissions circuits by use of a T1 framer idle code register.

The combination of the above five circuit techniques provides for the hardware implementation of a single printed circuit board embodiment (Line interface Unit LIU) of a plurality of communications functions including a T1 channel service unit, a ringing generator, power converters, a ringback tone generator, and a channel bank controller. The LIU supports selectable T1 standards of communications. Dual 12-channel telephone line voice cards plug into the LIU card to provide a complete T1 channel bank control process and apparatus. The invention solves telephone line interface, power filtering, ringing generation, and tone injection problems with lower component complexity, costs, and physical size than prior art solutions.

Claims

1. A DC power supply for a telephone terminating equipment located at the far end of a wire line, said DC power supply comprising:

a DC voltage power source;

a current regulated source I₁ connected in series to a positive lead of the DC voltage power source;

a current regulated sink I₂ connected in a series to a negative lead of the DC voltage power source and connected in a series to the current regulated source I₁ ;

an AC coupling device connected in series to said regulated current source I₁ and said current regulated sink I₂ ;

a first resistor R₁ in parallel with I₁ and a second resistor R₂ is parallel with I₂, whereby I_1- I₂₌ I_E and I₁ and I₂ maintain a high impedence state, thereby not significantly impairing an AC communications signal transmitted by said AC coupling device;

capacitor from said AC coupling device connected in series to the current regulated source I₁, functioning to prevent I₁, from flowing to the AC coupling device, and providing a circuit having excellent longitudinal balance performance and immunity to an induced noise.

2. The DC power supply of claim 1 further comprising a resistor connected in series with said capacitor wherein said capacitor and said resistor together provide an impedance match to an impedance of said wire line.

3. The DC power supply of claim 1, wherein the resistors R₁ and R₂ are selected such that a voltage V₁ across R₁ and a voltage V₂ across R₂ each remain in a range between V_max and V_min.

4. The DC power supply of claim 3, wherein the resistors R₁, R₂ are selected using the maximum voltage V_max and the minimum voltage V_min across the resistors and a maximum current I_max and a minimum current I_min through the resistors such that:

space="preserve" listing-type="equation">R.sub.1 =R.sub.2 =(V.sub.max -V.sub.min)/(I.sub.max -I.sub.min).

5.

5. The DC power supply of claim 1, wherein said DC voltage power source comprises a battery.

6. The DC power supply of claim 5, wherein said current regulated source I₁ is directly connected to a positive terminal of said battery.

7. The DC power supply of claim 6, wherein said current regulated sink I₂ is directly connected to a negative terminal of said battery.

8. The DC power supply of claim 7, wherein said first resistor R₁ is directly connected to a positive terminal of said battery.

9. The DC power supply of claim 8, wherein said second resistor R₂ is directly connected to a negative terminal of said battery.

10. The DC power supply of claim 1, wherein said first resistor R₁ is directly connected in parallel to said current regulated source I₁ without any intervening components therebetween.

11. The DC power supply of claim 1, wherein said second resistor R₂ is directly connected in parallel to said current regulated sink I₂ without any intervening components therebetween.

12. The DC power supply of claim 1, wherein said capacitor is directly connected to said current regulated source I₁.