Pre Filter
why Pre-emphasis are used and how they works?
Tell me the five uses of Pre emphasis filters.
I can think of 4 reasons.
1. In FM broadcast systems, in order to increase the signal-to-noise ratio for high frequency signals, the audio signal is boosted in the high frrequency range using an RC high-pass filter with a 3-dB cutoff of 13.333 kHz.
2. Coaxial cables all have a linear increase in attenuation versus frequency (when plotted on a log-log chart). The slope of the line is different for each type of coaxial cable, but high frequency attenuation is still present. In order to compensate for the high frequency loss through a coaxial cable, sometimes the high frequencies of a signal are increased (pre-emphasized) at the source end.
3. In old vinyl records, bass notes and low frequencies took up a lot of physical space on the recorded tracks so, in order to save space to allow more music to be recorded on a record the low frequencies were de-emphasized (which is the same basic form as saying the high frequencies were empahsizied). When the record was played back, an inverse function of the filter was applied in the preamp (called an RIAA preamp).
4. Digital audio requires sampling or digitizing the audio signal. By its nature there is a noise called quantization noise that is present no matter how good the system is. Quantization noise translates to high frequency noise when the digitized signal is converted back to an analog signal, so by pre-emphasizing the high frequency analog signal before it is digitized, you can increase the signal to noise ratio when it is converted for playback.
Note: there are other techniques that work a lot better than a high-pass filter for increasing signal-to-quantization_noise, but it is an example none-the-less.
5. If I come up with a 5th method I’ll edit this answer.
.
H3 Prefilter System — http://www.chansonalkalinewater.com
|
|
Uni Air Pre Filter KTM 950 02-06 990 07-08 $22.95 |
|
|
HONDA AFTERMARKET GX390 AIR FILTERS W/PRE-CLEANER $233.60 |
|
|
Honda CR 125/250 Maxima Pre Oiled Air Filter 0-07 $9.95 |
|
|
Honda CR 85 Maxima Pre Oiled Air Filter 86-07 $9.95 |
|
|
Honda CRF250 CRF 250 Maxima Pre Oiled Air Filter 04-09 $9.95 |
|
|
Honda CRF450 CRF 450 Maxima Pre Oiled Air Filter 02-08 $9.95 |
|
|
Honda CRF230 CRF 230 Maxima Pre Oiled Air Filter 03-09 $9.95 |
|
|
Village Marine 10″ Pre-Charged Filter $15.96 |
|
|
Honda CRF150 CRF 150 Maxima Pre Oiled Air Filter 03-09 $9.95 |
|
|
AEM DryFlow Pre-Filter Air Filter Wrap – AEM-1-4004 $31.95 |
|
|
AEM DryFlow Pre-Filter Air Filter Wrap – AEM-1-4003 $31.95 |
|
|
AEM DryFlow Pre-Filter Air Filter Wrap – AEM-1-4002 $31.95 |
|
|
Honda CRF150R 150 Maxima Pre Oiled Air Filter 07-10 $9.95 |
|
|
Honda CRF250 CRF 250 Maxima Pre Oiled Air Filter 2010 $9.95 |
|
|
Honda CRF450 CRF 450 Maxima Pre Oiled Air Filter 2010 $9.95 |
|
|
HONEYWELL ODOR Reducing Pre-FILTER $9.99 |
|
|
KOLHER AIR AND PRE-FILTER $12.95 |
|
|
EV9534-20 Everpure EC-210 Coarse Prefilter Sediment Water Cartridge # EV9534 $19.99 |
|
|
20″ Clear Big Blue Tankless Heater Pre-Sediment Filter $125.00 |
|
|
Pre Sediment Water Filter Titan Tankless Water Heater $36.99 |
|
|
MERCRUISER FUEL FILTER BASE PRE-ALPHA AND LINES $12.50 |
|
|
Ro Membrane Fits GE FX12P GE FX12M Pre & Post Filters $36.95 |
|
|
Sediment Whole House Pre Tankless Water Filter $15.00 |
|
|
Pre Tankless Water Filter with Bracket & Sediment Filter $19.99 |
|
|
Pre Sediment Filter for Tankless Water Heater $29.00 |
|
|
10.78×18.25x.38 inch P101-0001 Carrier Carbon Replacement Pre-Filters (2 Pack) $27.99 |
|
|
HONDA TRX450R TRX 450 R PRE FILTER BLACK $15.99 |
|
|
Homelite 49213 Felt Pre Filter XL98 Multi Purpose Saw $5.99 |
|
|
Homelite 49436 Felt Pre Filter DM40 Multi Purpose Saw $5.99 |
|
|
Water Factory Cuno 47-55706G2 Sediment Carbon Prefilter $27.99 |
|
|
K&N Universal Pre-Charger Filter Wrap ( 2″ Top 4″ Long ) RC-1200PK $20.95 |
|
|
Hunter QuietFlo Replacement Carbon Pre-Filter, Model 30901 2 ea $19.99 |
|
|
Honda TRX400EX Pre Oiled Air Filter 1999-2009 MOOSE $28.99 |
|
|
Air & Pre Filter for Honda Small Engines 17211-ZF5-V01 $13.49 |
|
|
Pre-Filter for Kohler Command CV11 – CV16/ 12 083 12-S $1.99 |
|
|
2 Hunter generic 30917 Purification Air Filters + 4 Pre-filters $21.99 |
|
|
10 Pack Genuine Kohler 20-883-02-S1 Air & Pre Filter $104.90 |
|
|
Dolmar PS 540 Chainsaw Covers Pre Air Filter $4.95 |
|
|
Eureka capture filter HF10 8800 8850 Pre Motor filter $29.99 |
|
|
BRIGGS & STRATTON FILTER – PRE CLEANER 805267S UNOPENED $3.95 |
|
|
HUNTER PERMALIFE 30547 Carbon Pre-Filter (2 Prefilters) Replaces Hunter 30901 $11.50 |
|
|
Fram TGA8243 Tough Guard Premium Air Filter – Pre-Oiled – Ford Ranger etc. $9.99 |
|
|
Air & Pre Filter For KAWASAKI 11013-2093 J DEERE M70284 $12.95 |
|
|
Kohler Engine PRE FILTER FOR K181 & M8 SERIES ENGINES. GOES WITH 2351_ 4108304-S $8.59 |
|
|
Briggs-Stratton Engine Air Filters Filter Cleaner; Uses 697292 Pre Filte_ 797007 $15.63 |
|
|
Twin Air Pre-Oiled Air Filter Kawasaki $27.95 |
|
|
Briggs-Stratton Engine Air Filters BRIGGS FILTER-PRE CLEANER 271794 BS-271794 $7.51 |
|
|
Briggs-Stratton Engine Air Filters BRIGGS FILTER PRE CL $8.08 |
|
|
Briggs-Stratton Engine BRIGGS FILTER-PRE CLEANER 491435S; GOES WITH BS-491435S $7.51 |
|
|
Briggs-Stratton Engine FILTER-PRE CL 492889 $8.17 |
|
|
Austin Air Healthmate Replacement Filter With Prefilter Lasts 5 Up To Years $49.99 |
|
|
Kawasaki Engine PRE FILTER FITS FB460V. USES 11013-2020 $17.01 |
|
|
Kohler Engine Air Filters PRE FILTER FOR CV17-745 M/V10-20 & SOME K_ KO-4508302S $14.19 |
|
|
Kohler Engine Air Filters Filter Foam Pre-Cleaner Fits 18-25h_ KO-Filter-2408302 $10.36 |
|
|
WASHABLE PRE-MOTOR TRAY & FILTER REPLACEMENT PART BISSELL MOMENTUM VAC VACUUM $1.99 |
|
|
SMALL ENGINE AIR AND PRE-FILTER REPLACES ONAN PART # 140-2597 $9.95 |
|
|
KOHLER AIR AND PRE FILTER PART # 1208305 & 1208308 $11.35 |
|
|
TECUMSEH AIR & PRE FILTER PART # 30604, 30727 $5.95 |
|
|
SMALL ENGINE AIR AND PRE-FILTER REPLACES TECUMSEH PART # 35403 FOR 8-13hp ENGINE $11.95 |
|
|
KOHLER AIR AND PRE FILTER PART # 4708303 K SERIES $8.95 |
|
|
BRIGGS AND STRATTON PRE FILTER PART # 491435 FOR 491588 $1.99 |
|
|
AIR AND PRE FILTER FOR HONDA GX240 GX270 PART # 17210-ZE2-822 AND MORE $10.95 |
|
|
BRIGGS AND STRATTON AIR & PRE FILTER PART # 496894 $14.25 |
|
|
Pre Sediment Filter for Tankless Water Heater $35.95 |
|
|
Bissell Pre-Motor Filter 203-1013 /3545 &-1 Powerglide $4.99 |
|
|
Aerobie 80R08 AeroPress Coffee and Espresso Maker … |
|
|
Bodum Brazil 8 cup French Press Coffee Maker, 34 oz, Black The Brazil French Press coffee maker, designed in the early 80′s, was our first coffee maker and quickly became a symbol of what Bodum stands for. Attractive and functional design at an affordable price The Brazil has an ultra-light, heat-resistant borosilicate glass beaker and a polypropylene handle and base, which make the Brazil easy to use and easy to clean. The 3-part stainless steel plunger … |
|
|
Bodum Chambord 8 cup French Press Coffee Maker, 34 oz., Chrome … |
|
|
Anthems for the Dammned $14.12 … |
|
|
Briggs & Stratton 491588S Flat Air Filter Cartridge $2.94 Brand New factory sealed Briggs and Stratton OEM FILTER-A/C CARTRIDGE. Current 2011 Briggs and Stratton part, Subject to availability from Briggs and Stratton. If not in stock you will be notified within 1 business day.. Check your Owners/Parts manual for correct application and fit. This is the current part description provided by the Original Equipment Manufacturer (OEM). To confirm your parts f… |
|
|
Miele Style G/N HyClean Vacuum Cleaner Bags: 4 Bags + 1 Super Air Clean Filter + 1 PreMotor Filter $15.51 This 9-layer bag with a protective netting seals up automatically via the spring-loaded hygiene shutter to ensure no dirt gets back into your house. The Miele GN Hyclean Dustbag has a hygiene shutter built-in to prevent dirt and debris from re-entering your house. The hygiene shutter is spring-loaded so as soon as you open the machine the shutter will close not allowing any dirt to escape. The col… |
|
|
Camco 40043 TastePURE RV Water Filter with Flexible Hose Protector $17.87 Looking for a large capacity in-line water filter? Look no further than TastePURE! The TastePURE RV Water Filter contains the KDF filtering system to fight bacteria, and reduce bad taste, odors, chlorine and sediment in drinking water. Convenient in-line exterior mount filter has a wider body to improve water flow; Comes with a no-kink hose protector. Durable welded case is UV resistant. Larger fi… |
|
|
Volant Pre-Filter $48.99 Pre-Filter; 6 in. PowerCore Filter; |
|
|
Danner 12605 Pre-Filter $9.43 Danner 12605 Pre-Filter Danner 12605 Pre-Filter Features: Coarse polyester and foam offer biological filtration Carbon impregnated media offers chemical and biological filtration, all offer mechanical filtration Pre-filter for MD1, MD 1.5, and MD 1.9 Pre-filter 3 per card |
|
|
EdgeStar Dehumidifier Pre-Filter $19 Replacement filter for the existing pre-filter that comes with the DEP400EW 40 pint dehumidifier. Rest easy knowing that your EdgeStar dehumidifier is able to provide both efficient moisture removal and clean incoming air. |
|
|
In-Line 40 Micron Pre-Filter $51.99 In-Line 40 Micron Pre-Filter; w/o Fittings; |