The calculations so far have assumed that there are only two carriers present. That is notalways the case in the real world. At the base station, one needs to account for not onlycarriers within an antenna system, but the stronger signals from nearby transmitters as well.The signals can backfeed into an antenna system, find nonlinear devices, mix with othercarriers, and create PIM. This issue compounds quickly when highly complex modulationplatforms are used; something that is already very evident in the cellular field, even whenrelatively narrow bandwidths are in use.
When the oxide layer is porous enough, the tunneling effect does not stop at 100 Angstroms.Corrosion from high humidity has a remarkable effect on steel and iron, creating unusuallystrong PIM distortion when there are rusty metallic structures in the signal path, or in thevicinity of strong transmitter signals. It has been suggested that the PIM is caused by thesemiconducting oxide of the corroded metal. However, experimental results in indicate thatthe major contributor could be the loose and small contact areas, rather than the corrodedjunction areas.
Careful cleaning, proper assembly, good weather wrapping, and proper connector torqueare the best solutions to connector caused PIM. Tooling must be kept clean, sharp and welladjusted. Unfortunately, the first instinct when a bad connection is identified is to over tightenthe components, which nearly always results in damage by deformation.
This type of test can be very handy when trying to find external materials that are causingPIM, such as loose flashing or other metalwork commonly used in building construction. Airconditioning ducts are particularly troublesome. Rarely are the mounts resistant to corrosion.
PIM over CPRI testing is a patented technology that enables PIM measurements to be made on a live system at ground level by monitoring regular LTE CPRI RF traffic. By tapping into the CPRI data on the downlink and uplink between the remote radio head (RRH) and baseband unit (BBU), PIM over CPRI testing can calculate the PIM desensitization of the LTE uplink. This measurement process tests real-world PIM scenarios, such as self-generated PIM (caused when multiple 15 kHz subcarriers making up the LTE signal mix and create intermodulation) as well as 2nd and 3rd order harmonics (e.g., 850 MHz downlink interfering with the 1700-2100 AWS uplink or the 900 downlink interfering with the 1800-2100 uplink). Because live traffic is being used, there are no calibrated 43 or 46 dBm two-tone continuous wave signals used, only the LTE subcarriers and resource blocks. Rather than a dBc result on a CW PIM signal, the PIM desensitization value (which can be thought of as the amount of noise inside your uplink signal, or the signal to PIM ration in dB) from the correlated PIM signal detected is measured and calculated. This test measurement works by synchronizing and comparing all of the available downlink MIMO signals of a sector (up to 2x MIMO) against each individual uplink signal. PIM over CPRI testing will also determine if the PIM found is internal or external to the antenna system.
PIM comes from two or more strong RF signals mixing in a non linear device. These non lineardevices, or junctions, occur in improperly tightened, damaged, or corroded connectors or indamaged antennas. Rusty components, such as mounts and bolts, are also suspect whenhunting for sources of PIM.
The first PC I ever used was an Apple IIc, somewheres around 1994, when Linux was three years old. A friend loaned it to me and it was all right, but too inflexible. Then I bought a used Tandy PC for something like $500, which was sad for the person who sold it because it cost a couple thousand dollars. Back then, computers depreciated very quickly. It was a monster: an Intel 386SX CPU, 4 megabytes RAM, a 107-megabyte hard drive, 14-inch color CRT monitor, running MS-DOS 5 and Windows 3.1.
Also remember when I came into touch with Linux the first very vividly. First had a book called 'Linux in 24 hours' which had a Red Hat 5.0 distribution. Later on I bought a distribution collector CD which contained several different. Remember we runned a lot of SuSE as well. But YaST was so damn slow. Preferred Red Hat more. Only the last 10 years it's all been about Debian and Ubuntu. (okay and I have had a period of using Gentoo)
"The first PC I ever used was an Apple IIc, somewheres around 1994, when Linux was three years old."Wow, this is information I totally was not aware of. Here I really thought Linus didn't release his OS to the hobbyists until October 1991:
Grace MacPherson, a teacher at Forest Street, recalled from 1900-1902, that manual training was established by Ned Warren at Warren School. This subject was open to boys and girls alike. The first item the girls made was a wedge. Physical Education was promoted by Cornelia Warren and one of the earliest instructors was Mr. Ross. Another thing to note, for years morning exercises were held for all classes in the Main Room. In 1912, the first Washington trip was held, at the cost of $32 per person. The chaperones for this trip were Mr. and Mrs. Andrews, the principal and his wife. The group took a train to Boston, but proceeded on to New York by boat. As they entered New York harbor early in the morning, they saw the Statue of Liberty. In the city they visited the Hippodrome. From New York they traveled to Philadelphia and saw such interesting sights as the U.S. Mint and the Liberty Bell. After leaving Washington, it took them five days to reach home. Basketball has always been an attraction at Westbrook High and in 1911, they went to the games on a trailer, hitched to the back of a trolley car. When Westbrook won the basketball championship in the years between 1913 and 1917, Hazel Wyer, a teacher in Westbrook, recalled how the students did a snake dance down Congress Street. The games were held at Cumberland Gym and plays, shows, etc., at the Star Theatre. The Woman's Relief Corps presented Westbrook High School with an American flag in 1918. In 1919, the Seniors taught some of the subjects to the lower classes because of a shortage of teachers. Harold Fernald, a student in 1920, remembered the days when the students from Pride's Corner came to school by horse-and-buggy while the students from White Rock came by train. That year the graduation was held outdoors at Warren Park. The Blue and White was published with class pictures for the first time in 1921, but these pictures were only snapshots. Miss Abbott, a history teacher at Westbrook High, came in 1925 when James Lewis was principal. In this year the Charleston became the dance craze and school was closed for the Gorham Fair.
4 Corners - (1) Bridge & Cumberland Streets; (2) Spring & County Road Little Canada - North Street, area of St. Hyacinth School Hottentot- old name for Cottage Place The Flats- lower Main Street, from City Hall to Riverside Street Cellar Field - sunken field bordered by Conant, New Gorham & Saco Street Scotch Hill- Bridge, Walker, Pike & Webb Streets Irish Hill- from Saco to Spring Street; the hill area Dagger Town- Polish neighborhood: Falmouth & George Streets French Town - Brown Street, from Bridge to Cumberland Streets "Pork" Hill- old name for what's now Park Hill; [this was a corruption of the name 'Park Hill' because the English garrison was situated there and the English ate a lot of pork, whereas the locals ate more beef Lost Nation - area off to the left side of Longfellow Street (after 108 Longfellow) that was not passable in mud season Duck Pond -US Rte. 302, Highland Lake region Saccarappa - original name of village at west end of Westbrook Pride's Corner-Rte 302 from Presumpscot River to comer of Brook & Bridgton Road (actual corner) The Village - Saccarappa Center Ammon Congin - old name for Cumberland Mills; original name of village at east end of Westbrook Cumberland Mills - area near Sappi (SD Warren Paper Mill); old village at east end of Westbrook Bird Land - development off County Road near Spring Street: Oriole, Cardinal, Finch, etc. Streets Brickyard- Hawke's Brickyard, Hawkes Street (where Hannafords is now) 1 st Spring- on Spring Street (area of golf course) 2nd Spring - on Spring Street (area of golf course) Old Car barns- (1) on Conant Street where bike shop is (2) at corner of Main & Saco Streets Centerville- Riverbank Park; this was the division between Saccarappa & Ammoncongin The "Star" - movie theater on Main Street & corner of Central Street (where Hub Furniture is) Underground Railroad - Brackett House, later Lafond's Store corner Main & Brackett Street The Sakokis- a river steam boat that went from Saccarappa Falls to Windham [another boat was named The Washington) 1 st Saw Mill - Conant Mill on Pork Hill Rialto - theater on Main Street, beside Star Theater; was on 2nd floor, later the Brook Theater Coconut Beach - east side of the river upriver, up above the fall [the Danas had a cottage there] Presumpscot - the river that divides the town; also the Presumpscot House, downtown Main Street Site of Corn Shop - on the riverbank in Cumberland Mills, where the swimming pool is now De clintons - local Hockey Team Roosevelt Trail- US Rte 302, name used only on the Windham end now King's Cove- Lincoln St, now skating rink; formed when Mr. King filled in the area on which to build a house on his farm [Haskell bought land from Mr. King in order to build his Silk Mill] Lamb's Hill- off Main Street as you enter the city; now called Deer Hill; the hilly area behind City Hall The Island (2) - (1) foot of Ash Street .. Indians lived there; when people fell in the river, their bodies washed up there (2) off the river bank below Fredette House King's Orchard - Lovers' Lane: Chestnut to Lincoln Streets Bean House - 3-story mansion built-by Joshua Webb, later converted into an apartment house by Woodbury' Dana; torn down in 1970s; was on Bridge Street near Brown Street. [remembered for its circular stairway & skylight J North School- originally at corner of Bridge & Pierce Streets; moved closer to S.D. Warren Mill & made into a private home in later years Christian Hill - Bridge St in area of old Bridge Street School; house at 146 Bridge Street was hauled from King's orchard and used as the meeting house . Berris Pond - beyond Bermside (large white home on right side of New Gorham Road) Bermside- Wise House, on New Gorham Road, beside the tow path Danish Neighborhood- Haskell Street, Libby & Boothby Avenue 2b1af7f3a8