Thursday, February 17, 2011

Wireless::Proveedores de Equipos

http://www.digitalstoreperu.com/tienda/category.php?id_category=18

Precios
http://www.diazcomunicaciones.com/tienda

Wireless Metrics

dBm is defined as power ratio in decibel (dB) referenced to one milliwatt (mW). It is an abbreviation for dB with respect to 1 mW and the "m" in dBm stands for milliwatt.

dBm is different from dB. dBm represents absolute power, whereas dB is a ratio of two values and is used to represent gain or attenuation. For example, 3 dBm means 2 mW, and 3 dB means a gain of 2. Similarly, -3 dBm means 0.5 mW, whereas -3 dB means attenuation of 2.

The formula to calculate dBm from mW is:

dBm = 10 log10( P )
1mW

Table of dBm and mW
http://www.guatewireless.org/internetworking/redes/wireless/tabla-de-relacion-entre-dbm-y-potencia-de-transmision-wlan/

Friday, February 04, 2011

Postgres Auditory

Trace connections
select * from pg_stat_activity;

select client_addr,count(*) from pg_stat_activity group by client_addr;

select datname,client_addr,count(*) from pg_stat_activity group by datname,client_addr;

Test times of count(*)

EXPLAIN ANALYZE SELECT COUNT(*) FROM remitos;

Obtain rows(tuples) info

select * from pg_class where relname = 'remitos' and relkind = 'r';
select * from pg_stat_all_tables where relname = 'remitos';

and look at the n_tup_ins, n_tup_del, ...


references:
http://www.postgresonline.com/journal/archives/134-Terminating-Annoying-Back-Ends.html

Thursday, February 03, 2011

Salesforce Test Visual Apex Pages

1) Page.existingPageName

2) PageReference pageRef = new PageReference('partialURL');
PageReference pageRef = new PageReference('/apex/HelloWorld');

3) PageReference pageRef = new PageReference('fullURL');
PageReference pageRef = new PageReference('http://www.google.com');

4) PageReference pageRef = ApexPages.currentPage();

Executing page:
https://c.na7.visual.force.com/apex/SecondAccount


References

Displaying JIRA related information in Salesforce.com
http://www.customware.net/repository/pages/viewpage.action?pageId=62455956

Wednesday, February 02, 2011

Wireless Punto a Punto :: Requisitos x distancia

Enlace punto a punto(requisitos x distancias):

Enlace 3Km entre 02 locales:
02 Antenas Hyperlink de 15 dBi (U$ 73 c/u)
02 AP(AccessPoint) TRENDnet de 54 Mbps (U$ 107 c/u)
02 pigtail de 60 cm (U$ 25 c/u)

Puede lograr enlaces de hasta 7Km usando AP(TRENDnet , DLINK , LINKsys , Edimax)


Enlace 8Km:
02 Antenas Hyperlink de 24 dBi (U$ 107 c/u)
02 AccessPoint(AP) Trendnet de 54 Mbps (U$ 110 c/u)
02 pigtail de 2 metros (U$ 34 c/u)


Enlace 1Km:
02 Antena Hyperlink Flat Panel de 14 dBi (U$ 45 c/u)
02 AP TP-LINK 54 Mbps (U$ 79 c/u)
02 Pigtail de 60 cm. (U$ 22 c/u)


Referencias
http://www.ds3comunicaciones.com/
http://www.opcionweb.com/index.php/2008/03/04/tipos-de-antenas-wifi/

Firefox open multiple private window

    /opt/firefox/firefox-bin --profile $(mktemp -d) --private-window www.google.com www.bing.com