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Recent content by bonsai

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    How We Test Wireless Products - Revison 7

    It's not only the cross polarization loss which hurts, but also the unequal distances between shielded box antennas and dut antennas. The actual criteria is to place front of the DUT 8 inches apart from the pickup-antennas. However, if any antenna is further away than 8 inches, the pathloss...
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    How We Test Wireless Products - Revison 7

    I think we are getting off-topic :rolleyes: Some years ago i read a paper, that one of the reasons for preferring OFDM at high data rates is that OFDM is significantly more economic from receiver implementation point of view (energy consumption and chip size). In single carrier systems, the...
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    How We Test Wireless Products - Revison 7

    These problems are the reason, why OFDM modulations became so successful and why WLAN was defined with so many modulation schemes. The data is splitted into 48 data-streams (per 20MHz) and each stream modulated to an own (sub) carrier frequency. Because the subcarrier bandwidth is much lower...
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    Antenna question

    This can't be generally answered: I can at least say, that there are some MIMO chipsets in the market (f.e Ralink), where one antenna is the "master" and the others are MIMO slaves. With these chipsets you can only establish a connection via the "master" antenna and establishing a connection...
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    How We Test Wireless Products - Revison 7

    You are talking about mobile standards where time variance is of high relevance and any dB of link budget or throughput improvement directly transfers into big money savings for the operators. This sort of simulations are usually done during development of the standard and perhaps also by...
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    How We Test Wireless Products - Revison 7

    The problem is that usually a propagation model shall simulate antennas plus propagation medium, which means the interface of the propagaion model is usually a (physical) RF connection (=conducted input/output) But by picking up the DUT RF singals "wireless" via probe antennas, effectively a...
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    How We Test Wireless Products - Revison 7

    @stevech Yes, for customer user experiendce it's difficult to distinguish 3dB more or less. @ Private Joker Indeed i am working in the field of wireless product development and therefore have to deal a lot with datasheets and technical articles which are only available in English...
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    How We Test Wireless Products - Revison 7

    There might have been some misunderstandings because english isn't my mother language and often i am in trouble finding the correct words and understanding the nuances between the lines. The test results of your 0°/45° comparison against the Asus router are expected. By rotating the antennas...
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    How We Test Wireless Products - Revison 7

    My understanding is, that "Thiggins" doesn't want to walk around any more and the new method with the chamber shall replace the walks. However, the benefit of walking around in a test house is to get a clue about the WLAN coverage of the product, mainly determined by tx power and receiver...
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    How We Test Wireless Products - Revison 7

    An "acustic" example for better understanding what i am talking about Receiving a MIMO signal can be compared to listening to stereo music. The better the stereo separation, the better the throughput . Think of a small (anechoic !) room with two loudspeakers inside, which are connected to...
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    How We Test Wireless Products - Revison 7

    Thanks for the many answers. I can fully understand the effort to reduce the test times by automation. Just want to make aware, that a "fair" test might require different chamber antenna setups, which individually depend on the antenna configuration of the router under test. When looking...
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    How We Test Wireless Products - Revison 7

    This is my first posting here :) First of all, i would like to thank you for this great Smallnetbuilder page, which already helped me several times to select "the good ones" out of the product Jungle. The "kick" to register to this forum was this article...
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