DATA STORAGE COMMUNICATION CHANNEL AND METHOD OF TRANSMITTING DATA

• US 20010050927A1
• Filed: 01/30/1998
• Published: 12/13/2001
• Est. Priority Date: 08/15/1997
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: JOHNSON, BRUCE E.
• Granted Patent: US 6,442,179 B2
• Time in Patent Office: Days
• US Class Current: 370/535
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0658 Controller construction arrangements
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11B 20/1403 characterised by the use of two levels

Abstract

A data storage communication channel includes a transmission medium, an initiator interface and a frequency selective multiplexer. The initiator interface includes first and second serial transmit ports. The frequency selective multiplexer includes first and second modulators and a circulator. The first and second modulators have first and second frequency bands and are coupled to the first and second serial transmit ports, respectively. The circulator is coupled between the first and second modulators and one end of the transmission medium.

Claims

1. A data storage communication channel comprising:

a transmission medium;

an initiator interface comprising first and second serial transmit ports for transmitting first and second serial transmit signals, respectively; and

a first frequency selective multiplexer comprising;

first and second modulators which are operatively coupled to the first and second serial transmit ports, respectively, and modulate the first and second serial transmit signals in first and second frequency bands, respectively, wherein the first frequency band is different than the second frequency band; and

a first circulator which is operatively coupled between the first and second modulators and the transmission medium and which combines the first and second modulated serial transmit signals into a first transmission signal and applies the first transmission signal to the transmission medium.

2. The data storage communication channel of

claim 1

wherein the transmission medium is selected from the group consisting of a copper cable, printed circuit board traces, an optical cable, an infrared communication link, and a radio frequency communication link.

3. The data storage communication channel of

claim 1

wherein the first and second modulators each comprise:

a mixer having a mixer receive port, a local oscillator port, and an intermodulation product port, wherein the mixer receive port is operatively coupled to the respective serial transmit port and the intermodulation product port is operatively coupled to the first circulator; and

a frequency synthesizer comprising a pre-scaler input, a reference clock input and a local oscillator output which is operatively coupled to the local oscillator port of the mixer.

4. The data storage communication channel of

claim 3

wherein the frequency synthesizer comprises:

a pre-scaler circuit which is operatively coupled to the pre-scaler input and the reference clock input and comprises a pre-scaled frequency output;

a phase/frequency detector having a reference input, a feedback input and a control voltage output, wherein the reference input is operatively coupled to the pre-scaled frequency output; and

a voltage controlled oscillator (VCO) having a control voltage input which is operatively coupled to the control voltage output and a VCO output which is operatively coupled to the feedback input and which defines the local oscillator output.

5. The data storage communication channel of

claim 1

and further comprising:

a first frequency selective demultiplexer comprising;

first and second demodulators which are operatively coupled to the transmission medium to receive the first transmission signal and which demodulate the first and second serial transmit signals from the first transmission signal in the first and second frequency bands, respectively; and

first and second data storage interfaces which are operatively coupled to the first and second demodulators, respectively, to receive the demodulated first and second serial transmit signals.

6. The data storage communication channel of

claim 5

wherein:

the transmission medium comprises first and second transmission paths, wherein the first transmission path is coupled between the first circulator and the first and second demodulators;

the initiator interface further comprises first and second serial receive ports;

the first data storage interface comprises a third receive port which is operatively coupled to the first demodulator and comprises a third transmit port for transmitting a third serial transmit signal;

the data storage communication channel further comprises a second frequency selective multiplexer and a second frequency selective demultiplexer;

the second frequency selective multiplexer comprises;

third and fourth modulators which are operatively coupled to the third and fourth serial transmit ports, respectively, and modulate the third and fourth serial transmit signals in the first and second frequency bands, respectively; and

a second circulator which is operatively coupled between the third and fourth modulators and the second transmission path and which combines the third and fourth modulated serial transmit signals into a second transmission signal and applies the second transmission signal to the second transmission path; and

the second frequency selective demultiplexer comprises;

third and fourth demodulators which are operatively coupled to the second transmission path to receive the second transmission signal and which demodulate the third and fourth serial transmit signals from the second transmission signal in the first and second frequency bands, respectively.

7. A data storage communication channel comprising:

a transmission medium for carrying a transmission signal having first and second serial, digital transmit signals modulated in first and second frequency bands, respectively;

a first frequency selective demultiplexer comprising;

first and second demodulators which are operatively coupled to the transmission medium to receive the first transmission signal and which demodulate the first and second serial, digital transmit signals from the first transmission signal in the first and second frequency bands, respectively; and

first and second data storage interfaces which are operatively coupled to the first and second demodulators, respectively, to receive the demodulated first and second serial transmit signals.

8. The data storage communication channel of

claim 7

wherein the first and second demodulators each comprise:

a mixer having a mixer receive port, a local oscillator port, and an intermodulation product port, wherein the mixer receive port is operatively coupled to the first transmission path and the intermodulation product port is operatively coupled to the first data storage interface; and

a frequency synthesizer comprising a pre-scaler input, a reference clock input and a local oscillator output which is operatively coupled to the local oscillator port of the mixer.

9. The data storage communication channel of

claim 7

and further comprising:

an initiator interface comprising first and second serial transmit ports for transmitting the first and second serial transmit signals, respectively; and

a first frequency selective multiplexer comprising;

first and second modulators which are operatively coupled to the first and second serial transmit ports, respectively, and modulate the first and second serial transmit signals in the first and second frequency bands, respectively, wherein the first frequency band is different than the second frequency band; and

a first circulator which is operatively coupled between the first and second modulators and the transmission medium and which combines the first and second modulated serial transmit signals into the transmission signal and applies the transmission signal to the transmission medium.

10. A data storage system backplane comprising:

a transmission media interface having a channel transmit port and a channel receive port;

first and second data storage interfaces, each data storage interface comprising a serial transmit port and a serial receive port;

a frequency selective multiplexer operatively coupled between the channel transmit port and the serial transmit ports of the first and second data storage interfaces; and

a frequency selective demultiplexer operatively coupled between the channel receive port and the serial receive ports of the first and second data storage interfaces.

11. The data storage system backplane of

claim 10

wherein:

the frequency selective multiplexer comprises;

a first modulator, operatively coupled to the serial transmit port of the first data storage interface and having a first modulation frequency band;

a second modulator, operatively coupled to the serial transmit port of the second data storage interface and having a second modulation frequency band, which is outside the first modulation frequency band; and

a circulator, operatively coupled between the channel transmit port, the first modulator and the second modulator; and

the frequency selective demultiplexer comprises;

a first demodulator, operatively coupled between the channel receive port and the serial receive port of the first data storage interface and having a first demodulation frequency band which corresponds to the first modulation frequency band; and

a second demodulator, operatively coupled between the channel receive port and the serial receive port of the second data storage interface and having a second demodulation frequency band which corresponds to the second modulation frequency band.

12. The data storage system backplane of

claim 11

wherein:

the first modulator comprises;

a first mixer having a mixer receive port, a local oscillator port, and an intermodulation product port, wherein the mixer receive port is operatively coupled to the serial transmit port of the first data storage interface and the intermodulation product port is operatively coupled to the circulator; and

a first frequency synthesizer comprising a pre-scaler input, a reference clock input and a local oscillator output which is operatively coupled to the local oscillator port of the first mixer; and

the first demodulator comprises;

a second mixer having a mixer receive port which is operatively coupled to the channel receive port, a local oscillator port which is operatively coupled to the local oscillator output of the first frequency synthesizer, and an intermodulation product port which is operatively coupled to the serial receive port of the first data storage interface.

13. The data storage system backplane of

claim 12

and further comprising:

a power supply terminal and a ground supply terminal; and

wherein the pre-scaler input comprises a plurality of frequency select input terminals which are operatively coupled to the power and ground supply terminals in a selected combination that corresponds to a pre-scaling factor; and

wherein the first frequency synthesizer comprises means for generating the local oscillator output as a function of the pre-scaling factor such that the local oscillator output defines a center frequency of the first modulation frequency band and the first demodulation frequency band.

14. The data storage system backplane of

claim 12

wherein:

the second modulator comprises;

a third mixer having a mixer receive port, a local oscillator port, and an intermodulation product port, wherein the mixer receive port of the third mixer is operatively coupled to the serial transmit port of the second data storage interface and the intermodulation product port is operatively coupled to the circulator; and

a second frequency synthesizer comprising a pre-scaler input, a reference clock input and a local oscillator output which is operatively coupled to the local oscillator port of the third mixer; and

the second demodulator comprises;

a fourth mixer having a mixer receive port which is operatively coupled to the channel receive port, a local oscillator port which is operatively coupled to the local oscillator output of the second frequency synthesizer, and an intermodulation product port which is operatively coupled to the serial receive port of the second data storage interface.

15. The data storage system backplane of

claim 11

and further comprising first and second circuit boards, wherein the first modulator and the first demodulator are mounted to the first circuit board and wherein the second modulator and the second demodulator are mounted to the second circuit board.

16. The data storage system backplane of

claim 10

and further comprising a circuit board, wherein the media interface, the frequency selective multiplexer and the frequency selective demultiplexer are mounted to the circuit board.

17. A method of transmitting a plurality of data signals from an initiator interface to a plurality of data storage interfaces which are operatively coupled to a data storage system backplane, the method comprising the steps of:

(a) frequency multiplexing the plurality of data signals together, wherein each of the plurality of data signals is modulated in a respective frequency band and wherein the respective frequency bands are separate from one another;

(b) transmitting the frequency multiplexed plurality of data signals to the data storage system backplane through a serial transmission medium;

(c) frequency demultiplexing the frequency multiplexed plurality of data signals received at the data storage system backplane, wherein each of the plurality of data signals is demodulated from the respective frequency band; and

(d) applying each of the frequency demultiplexed plurality of data signals to a respective one of the plurality of data storage interfaces.

18. A method of transmitting a plurality of data signals from a plurality of data storage interfaces, which are operatively coupled to a data storage system backplane, to an initiator interface, the method comprising the steps of:

(a) receiving each of the plurality of data signals from a respective one of the plurality of data storage interfaces, at the data storage system backplane;

(b) frequency multiplexing the plurality of data signals together, wherein each of the plurality of data signals is modulated in a respective frequency band and wherein the respective frequency bands are separate from one another;

(c) transmitting the frequency multiplexed plurality of data signals to the initiator interface through a serial transmission medium;

(d) frequency demultiplexing the frequency multiplexed plurality of data signals received at the initiator interface, wherein each of the plurality of data signals is demodulated from the respective frequency band; and

(e) applying each of the frequency demultiplexed plurality of data signals to a respective port of the initiator interface.

19. A data storage communication channel comprising:

a plurality of data storage interfaces; and

communication means for transmitting data to and receiving data from the plurality of data storage interfaces by frequency multiplexing the data over a transmission medium.