Преобразование недопустимого json в допустимый json

Я пытаюсь прочитать .json файл с веб-сервера. Сообщается, что JSON, который я получаю с сервера, недействителен по адресу http://jsonlint.com/ :

{
    preOpen: "900",
    preClose: "908",
    mktOpen: "915",
    mktClose: "1530",
    corrOpen: "1540",
    corrClose: "1600",
    mktStatusCode: "3",
    status: "MARKET OPEN",
    time: "Jan 11, 2012 12:32:14",
    data: [
        {
            name: "S&P CNX NIFTY Pre Open",
            lastPrice: "4,863.15",
            change: "13.60",
            pChange: "0.28",
            imgFileName: "S&P_CNX_NIFTY_Pre_Open_open.png"
        },
        {
            name: "S&P CNX NIFTY",
            lastPrice: "4,871.15",
            change: "21.60",
            pChange: "0.45",
            imgFileName: "S&P_CNX_NIFTY_open.png"
        },
        {
            name: "CNX NIFTY JUNIOR",
            lastPrice: "8,940.05",
            change: "91.90",
            pChange: "1.04",
            imgFileName: "CNX_NIFTY_JUNIOR_open.png"
        },
        {
            name: "BANK NIFTY",
            lastPrice: "8,816.15",
            change: "81.10",
            pChange: "0.93",
            imgFileName: "BANK_NIFTY_open.png"
        },
        {
            name: "INDIA VIX",
            lastPrice: "24.18",
            change: "0.18",
            pChange: "0.75",
            imgFileName: "INDIA_VIX_open.png"
        },
        {
            name: "CNX 100",
            lastPrice: "4,729.25",
            change: "25.05",
            pChange: "0.53",
            imgFileName: "CNX_100_open.png"
        },
        {
            name: "S&P CNX DEFTY",
            lastPrice: "3,265.00",
            change: "41.70",
            pChange: "1.29",
            imgFileName: "S&P_CNX_DEFTY_open.png"
        },
        {
            name: "S&P CNX 500",
            lastPrice: "3,811.75",
            change: "26.40",
            pChange: "0.70",
            imgFileName: "S&P_CNX_500_open.png"
        },
        {
            name: "CNX MIDCAP",
            lastPrice: "6,548.20",
            change: "80.65",
            pChange: "1.25",
            imgFileName: "CNX_MIDCAP_open.png"
        },
        {
            name: "NIFTY MIDCAP 50",
            lastPrice: "1,937.20",
            change: "21.30",
            pChange: "1.11",
            imgFileName: "NIFTY_MIDCAP_50_open.png"
        },
        {
            name: "CNX INFRA",
            lastPrice: "2,273.60",
            change: "8.50",
            pChange: "0.38",
            imgFileName: "CNX_INFRA_open.png"
        },
        {
            name: "CNX REALTY",
            lastPrice: "207.85",
            change: "8.10",
            pChange: "4.06",
            imgFileName: "CNX_REALTY_open.png"
        },
        {
            name: "CNX ENERGY",
            lastPrice: "7,300.55",
            change: "37.10",
            pChange: "0.51",
            imgFileName: "CNX_ENERGY_open.png"
        },
        {
            name: "CNX FMCG",
            lastPrice: "10,308.90",
            change: "10.90",
            pChange: "0.11",
            imgFileName: "CNX_FMCG_open.png"
        },
        {
            name: "CNX MNC",
            lastPrice: "4,660.35",
            change: "30.40",
            pChange: "0.66",
            imgFileName: "CNX_MNC_open.png"
        },
        {
            name: "CNX PHARMA",
            lastPrice: "4,743.15",
            change: "-4.15",
            pChange: "-0.09",
            imgFileName: "CNX_PHARMA_open.png"
        },
        {
            name: "CNX PSE",
            lastPrice: "2,753.90",
            change: "14.60",
            pChange: "0.53",
            imgFileName: "CNX_PSE_open.png"
        },
        {
            name: "CNX PSU BANK",
            lastPrice: "2,847.95",
            change: "22.80",
            pChange: "0.81",
            imgFileName: "CNX_PSU_BANK_open.png"
        },
        {
            name: "CNX SERVICE",
            lastPrice: "5,933.65",
            change: "21.65",
            pChange: "0.37",
            imgFileName: "CNX_SERVICE_open.png"
        },
        {
            name: "CNX IT",
            lastPrice: "6,300.35",
            change: "-31.40",
            pChange: "-0.50",
            imgFileName: "CNX_IT_open.png"
        },
        {
            name: "CNX SMALLCAP",
            lastPrice: "2,981.80",
            change: "49.85",
            pChange: "1.70",
            imgFileName: "CNX_SMALLCAP_open.png"
        },
        {
            name: "CNX 200",
            lastPrice: "2,432.05",
            change: "14.35",
            pChange: "0.59",
            imgFileName: "CNX_200_open.png"
        },
        {
            name: "CNX AUTO",
            lastPrice: "3,497.60",
            change: "4.05",
            pChange: "0.12",
            imgFileName: "CNX_AUTO_open.png"
        },
        {
            name: "CNX MEDIA",
            lastPrice: "1,147.30",
            change: "23.35",
            pChange: "2.08",
            imgFileName: "CNX_MEDIA_open.png"
        },
        {
            name: "CNX METAL",
            lastPrice: "2,746.95",
            change: "60.60",
            pChange: "2.26",
            imgFileName: "CNX_METAL_open.png"
        }
    ]
}

Отображается следующий результат теста:

Parse error on line 1:
{    preOpen: "900",    
-----^
Expecting 'STRING', '}'

Как я могу преобразовать его в VALID JSON перед его анализом с помощью PHP ??