1. A method for generating a preamble of a frame for a multiple input multiple output (MIMO) wireless communication, the method comprises:
for each transmit antenna of the MIMO wireless communication, generating a carrier detect field, wherein, from transmit antenna to transmit antenna;
for a first grouping of the transmit antennas of the MIMO wireless communication:
generating a first guard interval following the carrier detect field;
generating at least one channel sounding field with respect to each transmit antennas of the first grouping, wherein the at least one channel sounding field follows the first guard interval; and
for each transmit antenna of the first grouping, applying a cyclic shift prior to transmission; and
when the MIMO wireless communication includes more than the first grouping of the transmit antennas, for another grouping of the transmit antennas:
generating at least one other channel sounding field for each transmit antenna of the another grouping, wherein, from transmit antenna to transmit antenna in the another grouping, the at least one other channel sounding field follows the at least one channel sounding field; and
generating the first guard interval prior to the at least one other channel sounding field; and
for each transmit antenna of the another grouping, applying another cyclic shift prior to transmission of the another grouping.
2. The method of claim 1 further comprises, for each transmit antenna of the first grouping of the transmit antennas of the MIMO wireless communication:
generating a second guard interval following the at least one channel sounding field; and
generating a signal field following the second guard interval.
3. The method of claim 2 further comprises, for each transmit antenna of the another grouping of the transmit antennas:
generating a third guard interval preceding the at least one other channel sounding, wherein the first and third guard intervals are greater in duration than the second guard interval.
4. The method of claim 1, wherein the generating the carrier detect field comprises:
generating a short training sequence in accordance with a legacy protocol is based on a number of the transmit antennas and duration of the short training sequence.
5. The method of claim 4 further comprises, when the number of transmit antennas is three:
for the first grouping of the transmit antennas of the MIMO wireless communication, generating a first and second long training sequence in accordance with the legacy protocol as at least one channel sounding field, wherein the first grouping includes two of the three transmit antennas; and
generating a third long training sequence in accordance with the legacy protocol as the at least one other channel sounding field for the another grouping of the transmit antennas, wherein the another grouping includes a third of the three transmit antennas.
6. The method of claim 4 further comprises, when the number of transmit antennas is four:
for the first grouping of the transmit antennas of the MIMO wireless communication, generating a first and second long training sequence in accordance with the legacy protocol as at least one channel sounding field, wherein the first grouping includes two of the four transmit antennas; and
generating third and fourth long training sequences in accordance with the legacy protocol as at least one other channel sounding field for the another grouping of the transmit antennas, wherein the another grouping includes another two of the four transmit antennas.
7. The method of claim 1 further comprises for each of the transmit antennas of the MIMO wireless communication:
generating another guard interval following the at least one other channel sounding field; and
generating a second signal field following the another guard interval.
8. A method for generating a legacy compatible preamble of a frame for a multiple input multiple output (MIMO) wireless communication, the method comprises:
for each transmit antenna of a plurality of transmit antennas for the MIMO wireless communication, generating a carrier detect field, wherein, from transmit antenna to transmit antenna;
for a first transmit antenna of the plurality of transmit antennas:
generating a first guard interval following the carrier detect field;
generating a first channel sounding field following the first guard interval;
generating a second channel sounding field following the first channel sounding field; and
applying a cyclic shift prior to transmission via the first transmit antenna of the plurality of transmit antennas; and
for each transmit antenna of a first grouping of remaining transmit antennas of the plurality of transmit antennas:
generating a third channel sounding field;
generating a fourth channel sounding field following the third channel sounding field;
generating a second guard interval preceding the third channel sounding field; and
applying a cyclic shift prior to transmission via the each transmit antenna of the first grouping of the remaining transmit antennas.
9. The method of claim 8, wherein when the plurality of transmit antennas includes four transmit antennas:
for a fourth transmit antenna of the plurality of transmit antennas:
generating a fifth channel sounding field;
generating a sixth channel sounding field following the fifth channel sounding field; and
generating a third guard interval preceding the fifth channel sounding field.
10. The method of claim 9 further comprises for each of the plurality of transmit antennas:
generating another guard interval following the sixth channel sounding field; and
generating a signal field following the second guard interval.
11. The method of claim 8 further comprises, for the first transmit antenna:
generating another guard interval following the second channel sounding field; and
generating a signal field following the second guard interval.
12. The method of claim 8, wherein the generating the carrier detect field comprises:
generating a short training sequence in accordance with a legacy protocol is based on a number of the transmit antennas and duration of the short training sequence.
13. The method of claim 8 further comprises for each of the transmit antennas of the MIMO wireless communication:
generating another guard interval following the fourth channel sounding field; and
generating a second signal field following the another guard interval.
14. A radio frequency (RF) transmitter comprises:
a baseband processing module that produces outbound symbol streams from outbound data; and
a transmitter section that produces outbound RF signals from the outbound symbol streams, wherein the baseband processing module is operable to:
for each transmit antenna of the transmitter section, generate a carrier detect field, wherein, from transmit antenna to transmit antenna for a first grouping of the transmit antennas of the transmitter section:
generate a first guard interval following the carrier detect field;
generate at least one channel sounding field, wherein, from transmit antenna to transmit antenna in the first grouping, wherein the at least one channel sounding field follows the first guard interval; and
for each transmit antenna of the first grouping, applying a cyclic shift prior to transmission; and
when the transmitter section includes more than the first grouping of the transmit antennas, for another grouping of the transmit antennas:
generate at least one other channel sounding field, wherein, from transmit antenna to transmit antenna in the another grouping, wherein the at least one other channel sounding field follows the at least one channel sounding field; and
generate the first guard interval prior to the at least one other channel sounding field; and
for each transmit antenna of the another grouping, applying another cyclic shift prior to transmission of the another grouping.
15. The RF transmitter of claim 14, wherein the baseband processing module is further operable to, for each antenna of the first grouping of the transmit antennas of the transmitter section:
generate a second guard interval following the at least one channel sounding field; and
generate a signal field following the second guard interval.
16. The RF transmitter of claim 15, wherein the baseband processing module is further operable to, for each antenna of the another grouping of the transmit antennas:
generate a third guard interval preceding the at least one other channel sounding, wherein the first and third guard intervals are greater in duration than the second guard interval.
17. The RF transmitter of claim 14, wherein the baseband processing module is further operable to generate the carrier detect field by:
generating a short training sequence in accordance with a legacy protocol based on a number of the transmit antennas and duration of the short training sequence.
18. The RF transmitter of claim 17, wherein the baseband processing module is further operable to, when the number of transmit antennas is three:
for the first grouping of the transmit antennas of the transmitter section, generate a first and second long training sequence in accordance with the legacy protocol as at least one channel sounding field, wherein the first grouping includes two of the three transmit antennas; and
generate a third long training sequence in accordance with the legacy protocol as the at least one other channel sounding field for the another grouping of the transmit antennas, wherein the another grouping includes a third of the three transmit antennas.
19. The RF transmitter of claim 17, wherein the baseband processing module is further operable to, when the number of transmit antennas is four:
for the first grouping of the transmit antennas of the transmitter section, generate a first and second long training sequence in accordance with the legacy protocol as at least one channel sounding field, wherein the first grouping includes two of the four transmit antennas; and
generate third and fourth long training sequences in accordance with the legacy protocol as at least one other channel sounding field for the another grouping of the transmit antennas, wherein the another grouping includes another two of the four transmit antennas.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A test fixture for testing sheets of material comprising:
a cylinder having a side wall and a bottom surface defining an interior space for receiving at least one sheet of material to be tested; and
a piston slidable within said cylinder, said piston and said cylinder bottom surface cooperating for applying a holding force to said at least one sheet, said piston having a through hole for allowing a test medium to come into contact with said at least one sheet.
2. The test fixture according to claim 1 further comprising force applying means joined between said piston and said cylinder for applying a force to said piston and causing said piston maintain a position within said cylinder and into a position where said piston contacts a surface of said at least one sheet.
3. The test fixture according to claim 2 wherein said force applying means comprises:
a plurality of threaded studs connected to said cylinder at said cylinder side wall, said piston having a flange with a plurality of apertures therethrough corresponding to said plurality of studs for receiving said studs;
a spring means positionable on each said stud received in one said piston flange aperture; and
a nut threadable on each said stud, said nut compressing said spring means, and said spring means exerting force on said piston flange for ensuring that said piston remains in contact with said surface of said at least one sheet.
4. The test fixture according to claim 3 wherein said spring means comprises a Belleville washer.
5. The test fixture according to claim 1 wherein:
said piston has at least one annular groove formed on an exterior surface thereof; and
said test fixture further comprising a seal means positioned within said at least one annular groove for
preventing leakage between said piston and said cylinder.
6. The test fixture according to claim 5 wherein:
said piston has two spaced apart annular grooves; and
said seal means comprises an O-ring seated within each of said annular grooves.
7. A test fixture for testing sheets of material comprising:
a cylinder having a side wall and a bottom surface defining an interior space for receiving at least one sheet of material to be tested;
a piston having a flange positioned exterior of said cylinder and a body portion slidable within said cylinder, said flange and body portion defining a through hole inside said piston, and said piston body portion and said cylinder bottom surface cooperating for retaining said at least one sheet therebetween;
a sealing means positioned between said cylinder side wall and said piston body portion; and
a fastening means joined between said piston flange and said cylinder side wall for retaining said piston within said cylinder.
8. The test fixture according to claim 7 wherein said fastening means comprises:
a plurality of threaded studs connected to said cylinder at said cylinder side wall, said piston flange having a plurality of apertures therethrough corresponding to said plurality of studs for receiving said studs;
a spring means positionable on each said stud received in one said piston flange aperture; and
a nut threadable on each said stud, said nut compressing said spring means, and said spring means exerting force on said piston flange for ensuring that said piston remains in contact with said surface of said at least one sheet.
9. A process for allowing the assessment of chemical attack on thick elastomeric materials comprising:
providing a cylinder having an interior space;
positioning at least one sheet of elastomeric material within said interior space;
fastening a piston with a through hole within said cylinder for retaining said at least one sheet of elastomeric material within said interior space; and
immersing said cylinder with said at least one sheet and said piston into a test medium in which said chemical attack will be assessed.
10. The process according to claim 9 wherein said positioning step comprises positioning a stack of elastomeric sheets within said interior space.
11. The process according to claim 9 further comprising:
removing said cylinder and said fastened piston from said test medium;
removing said piston from said cylinder;
removing said at least one sheet from said interior space; and
measuring physical properties of each said at least one sheet.