Friday, August 20, 2010

What’s in a number? Rampant inflation of output power numbers among Wi-Fi vendors…

Many buyers come to us looking for the best available Wi-Fi adapter. One spec used to determine performance is RF output power, measured in both mW and dBm. Often potential customers believe the higher the output the better. This is not always the case, but output power is important. But how do you really know the true output power of the Wi-Fi product you are buying?

This month we completed a study of various high power Wi-Fi products being sold online at several market places and found there was rampant inflation of the output power declared for many items. For legal reasons we cannot name specific web sites or brand names at this time. What we can say is as follows:

1. Output power inflation was most common among generic Wi-Fi adapters. Because output power cannot be easily confirmed by the consumer, we found several online places that sold products advertised as 1000mW max output when in fact they were really 500mW or less.

2. If the product is advertised as having a brand name, it is a good idea to check with the manufacturer’s web site to confirm advertised specs. One brand name we can mention is Gsky- a maker of 500mW USB adapters. We obtained Gsky units from several vendors that advertised them as 1000mW when in fact they were really 500mW units. We also found that in many cases the specs of these products listed the dBm as 27 or 28 (which as any mW-to-dBm calculator confirms, is much less than 1000mW) even though other places in the descriptions referenced 1000mW.

3. Beware of those who advertise radiated output power. This is a trick whereby sellers can use a figure like 2000mW of 3000mW in the product title without actually claiming that it is the maximum RF output power of the product. This is done to confuse buyers and make a product appear more powerful than it is.

4. Beware of counterfeit products. When buying, if the product is brand name, check with the manufacturer to see if the seller is an authorized distributor of the brand. Just because they are not does not mean the product is counterfeit. We are not an authorized distributor of every brand we sell. But it does help narrow the chance. Some companies such as Alfa Networks sell only to authorized distributors. We are an authorized Alfa distributor and buying from an authorized Alfa distributor ensures you are getting a genuine product and also that your warranty is valid.

5. Always remember output power is only one specification. Other important areas to consider include the receive sensitivity of the chipset and the brand or seller of the product. A seller may advertise a product as coming with a 5 year warranty, but if the item is coming direct from China, are they really going to be there when the product breaks? Getting products such as Alfa Networks brand, which have been well reviewed online for several years, is a good way to ensure you are getting a quality product from a vendor with a good reputation.


McBeam said...

I've always wondered about this, seems like every product out there is 1000 mw now. Is there an easy way a consumer can verify the output of what they received?

Rokland LLC said...

There is no cheap and easy way to confirm for yourself. There are RF measuring devices you can hold near WiFi equipment but they do not give accurate results- the only way to get accurate results with WiFi equipment is a device like the Butterfly meter, which can be cost prohibitive for home use.

We recommend checking the manufacturer specs of any item to be sure they match the retailer's advertisement. But even manufacturers can inflate specs, so we recommend buying from a trusted manufacturer, such as Alfa networks.

Some people may try a comparison test, such as test an adapter vs. another model they know to have 1000mW. This is not a good way because it is possible for a product to have high output and lower receive sensitivity. So just because one product does not get the same signal strength as another, does not mean it does not have the same output power.

Senor said...

Nice article on avoiding dangers of "max" output ratings.

Im getting into the wifi discovery world, and am researching currently which wireless adapter to buy.

Alfa seems trustworthy...

Anonymous said...

As a satisfied Rokland customer I have this to add.

I bought an early Alfa abgn USB adapter that had a defective connector (that was improperly soldiered and worked loose.

Rokland cheerfully offered an RMA, and sent me a thoroughly tested unit no questions asked.

They are simply worth their money in customer service and support.

Thank you, Rokland.

Customer in Canada.